91
Locating Transmission Errors
Section 7-3
7-3
Locating Transmission Errors
The TR/ERR indicator may indicate an error before the END RS CHK indica-
tor goes off. If it does, the line may be disconnected or wired incorrectly, or
the power to one of the Units in the line may be off. To locate the problem,
set the Unit just before the end as the terminator, disconnect the cable to the
last Unit, and test the System again. Continue moving the terminator up one
Unit at a time until the Master is able to acknowledge a terminator. This will
let you know what section of the line the problem is in. Check the power sup-
ply and data transmission line connections for that section and test the Sys-
tem again.
The problem is here.
Terminator check
successful with this
Unit as terminator.
Terminator check
not successful with
this Unit as termina-
tor.
Original terminator
Slaves or Remote Terminals
Check the TR/ERR indicator of each Unit in the line to determine where the
error has occurred. The problem can then be corrected by repairing the
transmission line between the last Unit with the TR/ERR indicator flashing,
indicating normal transmission, and the first Unit with the TR/ERR indicator
lit, indicating an error.
Slaves or Remote Terminals
The problem is here.
TR/ERR indicator
flashing.
TR/ERR indicator
flashing.
TR/ERR indicator
flashing.
TR/ERR indicator
lit.
Before Terminator
Acknowledgement
After Terminator
Acknowledgement