Browse Prior Art Database

Loop Cabling System

IP.com Disclosure Number: IPCOM000048631D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 76K

Publishing Venue

IBM

Related People

Almquist, F: AUTHOR [+4]

Abstract

The addition of relays, switches and an auxiliary pair of wires signifincantly reduces the effect of disruptions caused by attaching terminals or wiring faults. The relays enable the terminals to connect and disconnect from the loop without disrupting the operation of other terminals on the loop, whereas the switches and auxiliary pair permit a logical loop to be configured from a variety of physical arrangements, or reconfigured to remove a faulty wiring segment, connection box or terminal, from the loop.

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Loop Cabling System

The addition of relays, switches and an auxiliary pair of wires signifincantly reduces the effect of disruptions caused by attaching terminals or wiring faults. The relays enable the terminals to connect and disconnect from the loop without disrupting the operation of other terminals on the loop, whereas the switches and auxiliary pair permit a logical loop to be configured from a variety of physical arrangements, or reconfigured to remove a faulty wiring segment, connection box or terminal, from the loop.

The figure shows the improved communication system. The communication system includes a main loop pair of wires 11 and an auxiliary loop pair of wires 13 in each cable. Terminal connection boxes (TCBs) 15, 23, 45, 49, 51, 55 for connecting processors or terminals, and wiring connection boxes (WCBs) 19, 25, 27 are joined by lengths of cable into effective loop, multidrop, or radial communication paths. Each TCB and WCB has a pair of switches A and B for diverting signals on the main pair onto the auxiliary pair to bypass, for example, a fault at 57. In addition to switches A and B, a pair of relays 1 and 2 are provided in each TCB to permit the terminal connected to the TCB to monitor communications on the loop for synchronization purposes prior to inserting its receiver R and transmitter T into the loop.

When the control line labeled monitor is connected to ground, relay 1 is actuated, permitting the receiver to monitor communications on the loop and look for the idle line signal (e.g., a continuous string of one bits), indicating that no messages are presently being sent from an upstream source. Although downstream terminals may be transmitting to controller 21, the actuation of relay 2 by grounding the insert line will not interrupt their transmission because only the idle line signal will be interfered with and this signal is not propagated by the communicating terminal but rather is replaced by the message being sent by the communicating terminal. Because relay 1 and relay 2 are under control of the terminal, the controller can use relay 1 and 2 to detect the location of a problem. For example, if the transmitter of terminal 47 is operating improperly, this improper operation can be detected at controller 21 if proper operation of the loop is restored after controller 21 commands terminal 47 to drop relay 2 in TCB
45. Dropping relay 2 causes the loop signal to propagate past terminal 47 but allows terminal 47 to continue receiving commands from the controller 21 through the points of relay 1 which is held in the monitor mode.

Note that when relay 1 is not...