Method and apparatus for backing up data transmission system

Claim 3

A method for backing up a data transmission system according to Claim 1 wherein each of said proc­essors contains a program to monitor the validity and normality of the operations of others, and said system service unit is frozen when an error is detected in any one of said processors.

Claim 4

A method for backing up a data transmission system according to Claim 2 wherein data transmission control is performed in a time sharing fashion between said system service unit and said slave station, and when no error of said system service unit is detected, said backup units are connected to said data trans­mission line in a manner to allow the execution of an off-line processing or a slave station fuction.

Claim 5

A method for backing up a data transmission system according to Claim 2 wherein said step (c) includes a sub-step of detecting error factors such as polling error, transmission carrier abnormality, line impkdance abnormality and absence of token from said data transmission line in said backup unit to produce representation of freezing of said system service unit.

Claim 6

A method for backing up a data transmission system according to Claim 3 wherein the representation of freezing is determined based on a combination of detected error factors.

Claim 7

A method for backing up a data transmission system according to Claim 1 wherein said step (c) includes the sub-steps of self-checking validity of the data transmission control operation in said backup unit when an error in the data transmission control operation of said system service unit is detected, and instructing a backup operation to said backup unit in accordance with the result of the self-check.

Claim 8

A method for backing up a data transmission system according to Claim 1 wherein said step (b) includes the sub-steps of, between a transmission/­reception terminal of one of said processors directly connected to said data transmission line and a sub-­central processing unit (sub-CPU) of said one processor executing an internal self-loop check of selecting an input supplied to the transmission terminal and execut­ing, in an intermediate period of the data transmission, an external self-loop check of selecting an output supplied from a reception terminal.

Claim 9

A method for backing up a data transmission system according to Claim 1 wherein said system service unit is connected to a central processing unit (CPU) (1) when it is normal, collectively processes data supplied from the slave station and the service unit, and when it is abnormal, it is backed up by said backup unit.

Claim 10

A method for backing up a data transmission system according to Claim 1 wherein said system service unit includes a main processor for controlling the entire unit and a sub-processor for performing a specific processing, as a multi-processor.

Claim 11

A data transmission processing system com­prising a data transmission service unit (3), a backup unit (4) having the same function as said service unit, at least one terminal (9) and a data transmission line (8) for connecting said terminal and said units, said service unit including: a main processor (5A, 5B) for controlling the entire unit; at least one sub-processor (6A, 6B) for performing a specific processing; error detection means (12, 19; 11, 18) located in said main processor and said sub-processor for mutually monitor the validity of the operation of other unit to detect an error in the unit; and disconnection means (22, 24, 27, 25) for disconnecting said service unit from said data trans­mission line in response to the output of said error detection means; said backup unit further including: backup start means (26, 29, 11-13) for detecting the disconnection of said system service unit through the data transmission line to start said backup unit.

Claim 12

A data transmission processing system com­prising a data transmission service unit (3), a backup unit (4) having the same function as said service unit, at least one terminal (9) and a data transmission line (8) for connecting said terminal and said units, said service unit including: a main processor (5A, 5B) for controlling the entire unit; at least one sub-processor (6A, 6B) for performing a specific processing; error detection means (12, 19; 11, 18) located in said main processor and said sub-processor for mutually monitor the validity of the operation of other unit to detect an error in the unit; and disconnection means (22, 24, 27, 25) for disconnecting said service unit from said data trans­mission line in response to the output of said error detection means; said backup unit further including: backup start means (26, 29, 11-13) for detecting the disconnection of said system service unit through the data transmission line to start said backup unit.

Claim 13

A data transmission processing system according to Claim 10 wherein said service unit and said terminal operate in a time sharing fashion in an on-line mode and said backup unit operates as one terminal in a normal state.

Claim 14

A data transmission processing system according to Claim 11 wherein said main processor and said sub-­processor of each of said units include means (12, 19) for storing recovery processing programs for detecting the error in the other unit.

Claim 15

A data transmission processing system according to Claim 19 wherein said backup unit includes means (29, 18) for detecting the absence of data transmission by an impedance of said data transmission line and means for ANDing the output of said absence detection means and the polling data error output from said service unit to determine occurrence of any error in said service unit.

Claim 16

A data transmission processing system according to Claim 10 wherein each of said service unit and said backup unit includes latch means (23) for indicating a master station, and means (2) is provided for selectively connecting said service unit or said backup unit to a central processing unit (1) for collectively processing data of the system, in response to the set output of said latch means.

Claim 17

A data transmission processing system according to Claim 10 wherein said data transmission line is an in-line or local area network.

Claim 18

A data transmission processing system according to Claim 10 wherein each of said service unit and said backup unit includes an additional sub-processor inter­connected to said main processor, and said sub-processor includes at least one of magnetic disk drive, floppy disk drive, magnetic card reader and file.

Claim 19

A data transmission system comprising at least one master unit (3) having a data transmission service function, at least one backup unit (4) having the same function as said master unit, a plurality of slave units (9) having terminal functions, and a data transmission line (8) for connecting said master unit, said backup unit and said slave units; said master unit and said backup unit each comprising a plurality of processor blocks (5A, 6A; 5B, 6B0 and disabling means (27, 25, 36) for disabling its own unit; said processor blocks each including error detection means (11, 12; 18, 19) for mutually monitoring validity and normality of operations of other processor blocks to detect any errors; said disabling means freezing the data trans­mission control operation of its own unit in responce to the output of said error detection means and discon­necting its own unit from said data transmission line; and said backup unit further comprising means (29, 26, 11, 12) for detecting the frozen status of the operation of said master unit based on the status of said data transmission line and signals therefrom and starting said backup unit in response to the detected output.

Claim 20

A data transmission system comprising at least one master unit (3) having a data transmission service function, at least one backup unit (4) having the same function as said master unit, a plurality of slave units (9) having terminal functions, and a data transmission line (8) for connecting said master unit, said backup unit and said slave units; said master unit and said backup unit each comprising a plurality of processor blocks (5A, 6A; 5B, 6B0 and disabling means (27, 25, 36) for disabling its own unit; said processor blocks each including error detection means (11, 12; 18, 19) for mutually monitoring validity and normality of operations of other processor blocks to detect any errors; said disabling means freezing the data trans­mission control operation of its own unit in responce to the output of said error detection means and discon­necting its own unit from said data transmission line; and said backup unit further comprising means (29, 26, 11, 12) for detecting the frozen status of the operation of said master unit based on the status of said data transmission line and signals therefrom and starting said backup unit in response to the detected output.