Communication switching marker having continuity testing and path controlling arrangement

Claim 1

IN A COMMUNICATION SWITCHING SYSTEM OPERATIVE TO ESTABLISH CONNECTIONS BETWEEN A FIRST SET OF TERMINALS AND A SECOND SET OF TERMINALS THROUGH A PLURALITY OF SWITCHING STAGES ARRANGED IN TANDEM BETWEEN TERMINALS OF THE FIRST SET AND TERMINALS OF THE SECOND SET, EACH OF SAID STAGES HAVING A PLURALITY OF RELAYS ARRANGED IN COORDINATE ARRAYS, EACH RELAY INCLUDING A HOLD WINDING, WITH A NORMALLY OPEN SET OF ITS HOLD PATH CONTACT CONNECTED IN SERIES WITH ITS HOLD WINDING, INTERSTAGE LINKS INTERCONNECTING ADJACENT STAGES, EACH INCLUDING A HOLD CONDUCTOR INTERCONNECTING THE SERIES COMBINATION OF THE HOLD WINDING AND THE NORMALLY OPEN CONTACTS OF A RELAY IN EACH OF THE ADJACENT STAGES, EACH SAID SET OF INTERSTAGE LINKS HAVING A SET OF LINK TEST LEADS CONNECTED TO RESPECTIVE HOLD CONDUCTORS, BUSY LINKS HAVING THE HOLD PATH CONTACTS CLOSED AT EACH END AND HAVING HOLDING CURRENT FLOWING THROUGH THE HOLD WINDINGS TO CAUSE A GIVEN POTENTIAL TO APPEAR TO THE HOLD CONDUCTOR, AND CONNECT MEANS OPERATE DURING THE TESTING FOR SELECTING A GROUP OF POSSIBLE LINKS FOR A GIVEN CONNECTION AND FOR CONNECTING THE LINK TEST LEADS THEREOF TO INDIVIDUAL INPUTS IN A PATH SELECTOR; THE IMPROVEMENT COMPRISING: MEANS TO APPLY A TEST POTENTIAL VIA IMPEDANCE DEVICES TO EACH SAID HOLD CONDUCTOR OF EACH INTERSTAGE LINK; AND A DETECTING MEANS TO TEST FOR THE PRESENCE OF SAID TEST POTENTIAL AT SAID PATH SELECTOR INPUTS VIA SAID CONNECT MEANS TO THEREBY DETERMINE THE CONTINUITY OF SAID LINK TEST LEADS.