Industrial control systems having input/output circuits with programmable input/output characteristics

Claim 2

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal Is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; and (C) a control-side I/O terminal, the control-side I/O terminal being coupled to the signal conditioning circuitry, (1) wherein, in the first mode of operation, the control-side I/O terminal receives an output of the signal conditioning circuitry, the output of the signal conditioning circuitry being produced by the signal conditioning circuitry based upon the analog input status signal to provide the input status of the analog input device at the control-side I/O terminal, and (2) wherein, in the second mode of operation, the control-side I/O terminal provides an input to the signal conditioning circuitry, the input to the signal conditioning circuitry being used by the signal conditioning circuitry to produce the analog output control signal to provide the desired output status of the analog output device at the device-side I/O terminal.

Claim 3

A programmable analog I/O circuit according to claim 1 , wherein the programmable analog I/O circuit further has third and fourth modes of operation, the third mode of operation being as an input circuit, and the fourth mode of operation being as an output circuit; and (1) wherein, in the first mode of operation, the analog input status signal is an input voltage signal having an input voltage level that indicates the input status of the analog input device, (2) wherein, in the second mode of operation, the analog output control signal is an output voltage signal having an output voltage level that indicates a desired output status of the analog output device, (3) wherein, in the third mode of operation, the analog input status signal is a current signal having a current level that indicates the input status of the analog input device, (4) wherein, in the fourth mode of operation, the analog output control signal is a current signal having a current level that indicates the desired output status of the analog output device.

Claim 4

A programmable analog I/O circuit according to claim 1 , wherein the signal conditioning circuitry comprises an operational amplifier, the operational amplifier receiving the analog input status signal as an input in the first mode of operation and producing the analog output control signal as an output in the second mode of operation.

Claim 5

A programmable analog I/O circuit according to claim 1 , wherein the signal conditioning circuitry comprises an operational amplifier, the operational amplifier having an output and an input that are both capable of being selectively coupled to either the device-side I/O terminal or to the control side I/O terminal; wherein, in the first mode of operation, the output of the operational amplifier is coupled to the control-side I/O terminal and the input of the operational amplifier is coupled to the device-side I/O terminal; and wherein, in the second mode of operation, the output of the operational amplifier is coupled to the device-side I/O terminal and the input of the operational amplifier is coupled to the control-side I/O terminal.

Claim 6

A programmable analog I/O circuit according to claim 1 , wherein the programmable analog I/O circuit forms an I/O channel of a rack-mountable I/O module.

Claim 7

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein the programmable analog I/O circuit further has third and fourth modes of operation, the third mode of operation being as an input circuit, and the fourth mode of operation being as an output circuit; and (1) wherein, in the first mods of operation, the analog input status signal is a first voltage signal having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal having a second voltage level that indicates the input status of the analog input device, the second voltage signal having a range of possible voltages different than the range of possible voltages of the first voltage signal, (2) wherein, in the second mode of operation, the analog output control signal is a third voltage signal having a third voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a fourth voltage signal having a fourth voltage level that indicates the desired output status of the analog output device, the fourth voltage signal having a range of possible voltages different than the range of possible voltages of the third voltage signal, (3) wherein, in the third mode of operation, the analog input status signal is a current signal having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal having a voltage level that indicates the input status of the analog input device, and (4) wherein, in the fourth mode of operation, the analog output control signal is a current signal having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal having a voltage level that indicates a desired output status of the analog output device.

Claim 8

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein the programmable analog I/O circuit further has third and fourth modes of operation, the third mode of operation being as an input circuit, and the fourth mode of operation being as an output circuit; and (1) wherein, in the first mods of operation, the analog input status signal is a first voltage signal having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal having a second voltage level that indicates the input status of the analog input device, the second voltage signal having a range of possible voltages different than the range of possible voltages of the first voltage signal, (2) wherein, in the second mode of operation, the analog output control signal is a third voltage signal having a third voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a fourth voltage signal having a fourth voltage level that indicates the desired output status of the analog output device, the fourth voltage signal having a range of possible voltages different than the range of possible voltages of the third voltage signal, (3) wherein, in the third mode of operation, the analog input status signal is a current signal having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal having a voltage level that indicates the input status of the analog input device, and (4) wherein, in the fourth mode of operation, the analog output control signal is a current signal having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal having a voltage level that indicates a desired output status of the analog output device.

Claim 9

An industrial control system comprising: (A) a plurality of input devices; (B) a plurality of output devices; (C) a programmable controller processor module, the processor module executing a control program to control the output status of the plurality of output devices based on the input status of the plurality of input devices; and (D) a programmable analog I/O module, the programmable analog I/O module being coupled to the processor module, the programmable analog I/O module including a programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit including (1) a device-side I/O terminal, (a) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input device being one of the plurality of input devices, and the analog input status signal indicating an input status of the analog input device, (b) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output device being one of the plurality of output devices, and the analog output control signal indicating a desired output status of the analog output device; (2) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (a) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (b) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; and (3) a control-side 1 o terminal, the control-side I/O terminal being coupled to the signal conditioning circuitry, (a) wherein, in the first mode of operation, the control-side I/O terminal receives an output of the signal conditioning circuitry, the output of the signal conditioning circuitry being produced by the signal conditioning circuitry based upon the analog input status signal to provide the input status of the analog input device at the control-side I/O terminal, (b) wherein, in the second mode of operation, the control-side I/O terminal provides an input to the signal conditioning circuitry, the input to the signal conditioning circuitry being used by the signal conditioning circuitry to produce the analog output control signal to provide the desired output status of the analog output device at the device-side I/O terminal.

Claim 10

An industrial control system comprising: (A) a plurality of input devices; (B) a plurality of output devices; (C) a programmable controller processor module, the processor module executing a control program to control the output status of the plurality of output devices based on the input status of the plurality of input devices; and (D) a programmable analog I/O module, the programmable analog I/O module being coupled to the processor module, the programmable analog I/O module including a programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit including (1) a device-side I/O terminal, (a) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input device being one of the plurality of input devices, and the analog input status signal indicating an input status of the analog input device, (b) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output device being one of the plurality of output devices, and the analog output control signal indicating a desired output status of the analog output device; (2) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (a) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (b) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; and (3) a control-side 1 o terminal, the control-side I/O terminal being coupled to the signal conditioning circuitry, (a) wherein, in the first mode of operation, the control-side I/O terminal receives an output of the signal conditioning circuitry, the output of the signal conditioning circuitry being produced by the signal conditioning circuitry based upon the analog input status signal to provide the input status of the analog input device at the control-side I/O terminal, (b) wherein, in the second mode of operation, the control-side I/O terminal provides an input to the signal conditioning circuitry, the input to the signal conditioning circuitry being used by the signal conditioning circuitry to produce the analog output control signal to provide the desired output status of the analog output device at the device-side I/O terminal.

Claim 11

A programmable analog I/O circuit according to claim 7 , wherein the signal conditioning circuitry comprises an operational, amplifier, the operational amplifier receiving the analog input status signal as an input in the first mode of operation and producing the analog output control signal as an output in the second mode of operation.

Claim 12

An industrial control system according to claim 7 , further comprising a rack in which are disposed the I/O module and a plurality of additional modules.

Claim 13

An industrial control system according to claim 7 , wherein the programmable analog I/O circuit further has third and fourth modes of operation, the third mode of operation being as an input circuit, and the fourth mode of operation being as an output circuit; and (1) wherein, in the first mods of operation, the analog input status signal is a first voltage signal having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal having a second voltage level that indicates the input status of the analog input device, the second voltage signal having a range of possible voltages different than the range of possible voltages of the first voltage signal, (2) wherein, in the second mode of operation, the analog output control signal is a third voltage signal having a third voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a fourth voltage signal having a fourth voltage level that indicates the desired output status of the analog output device, the fourth voltage signal having a range of possible voltages different than the range of possible voltages of the third voltage signal, (3) wherein, in the third mode of operation, the analog input status signal is a current signal having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal having a voltage level that indicates the input status of the analog input device, and (4) wherein, in the fourth mode of operation, the analog output control signal is a current signal having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal having a voltage level that indicates a desired output status of the analog output device.

Claim 14

An industrial control system according to claim 7 , wherein the I/O circuit further comprises a plurality of switches, the plurality of switches determining the configuration of the I/O circuit as either an input circuit or an output circuit.

Claim 15

An industrial control system according to claim 11 , wherein the plurality of switches are MOS transistors.

Claim 16

An industrial control system according to claim 11 , wherein the plurality of switches are micro-electromechanical switches.

Claim 17

An industrial control system according to claim 11 , wherein the plurality of switches are mechanical relays.

Claim 18

An industrial control system according to claim 11 , wherein the plurality of switches are controlled by the processor module.

Claim 19

An industrial control system comprising: (A) a plurality of analog input devices, each of the plurality of analog input devices transmitting an analog input status signal that varies between a minimum input value and a maximum input value, the analog input status signal indicating an input status of a respective analog input device; (B) a plurality of analog output devices, each of the plurality of analog output devices receiving an analog output control signal that varies between a minimum output value and a maximum output value, the analog output control signal controlling an output status of a respective analog output device: (C) a programmable controller processor module, the processor module executing a control program to control the output status of the plurality of output devices based on the input status of the plurality of input devices; (D) a programmable analog I/O module, the programmable analog I/O module including (1) a first plurality of programmable analog I/O circuits, each of the first plurality of programmable analog I/O circuits including a control-side I/O terminal and a device-side I/O terminal, and each of the first plurality of programmable analog I/O circuits being configured as an input circuit such that each the first plurality of programmable analog I/O circuits (a) is electrically connected between the processor module and a respective analog input device, (b) receives the analog input status signal from the respective analog input device by way of the device-side I/O terminal, and (c) produces an output at a control-side I/O terminal, the output being produced based on the analog input status signal and being used by the programmable analog I/O module to provide the processor module with the input status of the respective analog input device; (2) a second plurality of programmable analog I/O circuits, each of the second plurality of programmable analog I/O circuits including a control-side 10 terminal and a device-side I/O terminal, and each of the second plurality of programmable analog I/O circuits being configured as an output circuit such that each of the second plurality of programmable analog I/O circuits (a) is electrically connected between the processor module and a respective analog output device, (b) receives an input at the control-side I/O terminal and uses the input to produce the analog output control signal, and (c) provides the respective analog output device with the analog output control signal by way of the device-side I/O terminal, (3) a device-side I/O terminal block, the device-side I/O terminal block including the device-side I/O terminals of each of the first plurality of programmable analog I/O circuits and the device-side I/O terminals of each of the second plurality of programmable analog I/O circuits; wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits is adapted to be configured as either an input circuit or as an output circuit; wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits uses the same respective control-side I/O terminal to communicate with the processor module, regardless whether the respective programmable analog I/O circuit is configured as an input circuit or as an output circuit; and wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits uses the same respective device-side I/O terminal to communicate with analog I/O devices, regardless whether the respective programmable analog I/O circuit is configured as an input circuit or as an output circuit.

Claim 20

An industrial control system comprising: (A) a plurality of analog input devices, each of the plurality of analog input devices transmitting an analog input status signal that varies between a minimum input value and a maximum input value, the analog input status signal indicating an input status of a respective analog input device; (B) a plurality of analog output devices, each of the plurality of analog output devices receiving an analog output control signal that varies between a minimum output value and a maximum output value, the analog output control signal controlling an output status of a respective analog output device: (C) a programmable controller processor module, the processor module executing a control program to control the output status of the plurality of output devices based on the input status of the plurality of input devices; (D) a programmable analog I/O module, the programmable analog I/O module including (1) a first plurality of programmable analog I/O circuits, each of the first plurality of programmable analog I/O circuits including a control-side I/O terminal and a device-side I/O terminal, and each of the first plurality of programmable analog I/O circuits being configured as an input circuit such that each the first plurality of programmable analog I/O circuits (a) is electrically connected between the processor module and a respective analog input device, (b) receives the analog input status signal from the respective analog input device by way of the device-side I/O terminal, and (c) produces an output at a control-side I/O terminal, the output being produced based on the analog input status signal and being used by the programmable analog I/O module to provide the processor module with the input status of the respective analog input device; (2) a second plurality of programmable analog I/O circuits, each of the second plurality of programmable analog I/O circuits including a control-side 10 terminal and a device-side I/O terminal, and each of the second plurality of programmable analog I/O circuits being configured as an output circuit such that each of the second plurality of programmable analog I/O circuits (a) is electrically connected between the processor module and a respective analog output device, (b) receives an input at the control-side I/O terminal and uses the input to produce the analog output control signal, and (c) provides the respective analog output device with the analog output control signal by way of the device-side I/O terminal, (3) a device-side I/O terminal block, the device-side I/O terminal block including the device-side I/O terminals of each of the first plurality of programmable analog I/O circuits and the device-side I/O terminals of each of the second plurality of programmable analog I/O circuits; wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits is adapted to be configured as either an input circuit or as an output circuit; wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits uses the same respective control-side I/O terminal to communicate with the processor module, regardless whether the respective programmable analog I/O circuit is configured as an input circuit or as an output circuit; and wherein each of the first plurality of programmable analog I/O circuits and each of the second plurality of programmable analog I/O circuits uses the same respective device-side I/O terminal to communicate with analog I/O devices, regardless whether the respective programmable analog I/O circuit is configured as an input circuit or as an output circuit.

Claim 21

An industrial control system according to claim 16 , wherein the I/O module is rack-mountable, and further comprising a rack in which are disposed the I/O module and a plurality of additional modules.

Claim 22

An industrial control system according to claim 16 , wherein the I/O module and the processor module are disposed in separate racks and are connected by way of a communication link.

Claim 23

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mods of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the first mode of operation, the analog input status signal is a first voltage signal V in having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal V c having a second voltage level that indicates the input status of the analog input device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V in , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V in and the second voltage signal V c are related by an equation having the form V c =V ref k 1 −V in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 24

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mods of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the first mode of operation, the analog input status signal is a first voltage signal V in having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal V c having a second voltage level that indicates the input status of the analog input device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V in , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V in and the second voltage signal V c are related by an equation having the form V c =V ref k 1 −V in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 25

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output: wherein, in the first mode of operation, the analog input status signal is a current signal I in having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal V c having a voltage level that varies between a minimum input value and a maximum input value and that indicates the input status of the analog input device, and wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I in are related by an equation having the form V c =V ref k 1 −I in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 26

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output: wherein, in the first mode of operation, the analog input status signal is a current signal I in having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal V c having a voltage level that varies between a minimum input value and a maximum input value and that indicates the input status of the analog input device, and wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I in are related by an equation having the form V c =V ref k 1 −I in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 27

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the second mode of operation, the analog output control signal is a first voltage signal V out having a first voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a second voltage signal V c having a second voltage level that indicates the desired output status of the analog output device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V out , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V out and the second voltage signal V c are related by an equation having the form V out =V ref k 1 −V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 28

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the second mode of operation, the analog output control signal is a first voltage signal V out having a first voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a second voltage signal V c having a second voltage level that indicates the desired output status of the analog output device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V out , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V out and the second voltage signal V c are related by an equation having the form V out =V ref k 1 −V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 29

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the second mode of operation, the analog output control signal is a current signal I out having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal V c having a voltage level that varies between a minimum output value and a maximum output value and that indicates a desired output status of the analog output device, wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I out are related by an equation having the form I out =V s k 1 +V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V s is a supply voltage.

Claim 30

A programmable analog I/O circuit for use in an industrial control system, the programmable analog I/O circuit having first and second modes of operation, the first mode of operation being as an input circuit, and the second mode of operation being as an output circuit, the programmable analog I/O circuit comprising: (A) a device-side I/O terminal, (1) wherein, in the first mode of operation, the device-side I/O terminal is adapted for receiving an analog input status signal from an analog input device, the analog input status signal indicating an input status of the analog input device, (2) wherein, in the second mode of operation, the device-side I/O terminal is adapted for transmitting an analog output control signal to an analog output device, the analog output control signal indicating a desired output status of the analog output device; and (B) signal conditioning circuitry, the signal conditioning circuitry being coupled to the device-side I/O terminal, (1) wherein, in the first mode of operation, the signal conditioning circuitry receives the analog input status signal as an input, and (2) wherein, in the second mode of operation, the signal conditioning circuitry produces the analog output control signal as an output; wherein, in the second mode of operation, the analog output control signal is a current signal I out having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal V c having a voltage level that varies between a minimum output value and a maximum output value and that indicates a desired output status of the analog output device, wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I out are related by an equation having the form I out =V s k 1 +V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V s is a supply voltage.

Claim 31

An industrial control system according to claim 7 , wherein, in the second mode of operation, the analog output control signal is a current signal I out having a current level that indicates the desired output status of the analog output device and, to produce the analog output control signal, the signal processing circuitry uses a voltage signal V c having a voltage level that varies between a minimum output value and a maximum output value and that indicates a desired output status of the analog output device, wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I out are related by an equation having the form I out =V s k 1 +V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V s is a supply voltage.

Claim 32

An industrial control system according to claim 7 , wherein, In the first mode of operation, the analog input status signal is a first voltage signal V in having a first voltage level that indicates the input status of the analog input device and, based on the analog input status signal, the signal conditioning circuitry produces a second voltage signal V c having a second voltage level that indicates the input status of the analog input device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V in , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V in and the second voltage signal V c are related by an equation having the form V c =V ref k 1 −V in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 33

An industrial control system according to claim 7 , wherein, in the first mode of operation, the analog input status signal is a current signal I in having a current level that indicates the input status of the analog input device and, based upon the analog input status signal, the signal conditioning circuitry produces a voltage signal V c having a voltage level that varies between a minimum input value and a maximum input value and that indicates the input status of the analog, input device, and wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the voltage signal V c and the current signal I in are related by an equation having the form V c =V ref k 1 −V in k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.

Claim 34

An industrial control system according to claim 7 , wherein, in the second mode of operation, the analog output control signal is a first voltage signal V out having a first voltage level that indicates a desired output status of the analog output device and, to produce the analog output control signal, the signal conditioning circuitry uses a second voltage signal V c having a second voltage level that indicates the desired output status of the analog output device, the second voltage signal V c having a range of possible voltages different than the range of possible voltages of the first voltage signal V out , wherein the signal conditioning circuitry comprises a plurality of resistors, and wherein the first voltage signal V out and the second voltage signal V c are related by an equation having the form V out =V ref k 1 −V c k 2 where k 1 and k 2 are constants determined by the plurality of resistors in the signal conditioning circuitry and V ref is a reference voltage.