Siemens TC12 Installation, Commissioning And Maintenance Handbook page 160

If ONLY any of the following faults are recorded when in Outstation or Monitor
mode, Whilst OTUs respond with out faults to test set in Instation mode:
RTS (amber led) on Instation modem board not lighting
On test set, both Control and Reply Idle or only Control Idle, and/or CD indicator
not showing carrier being detected.
POSSIBLE FAULT: Instation not transmitting.
If ONLY any of the following faults are recorded when in Instation or Monitor
mode, Whilst UTC TCC/Instation see no faults with test set simulating the OTU,
i.e. in Outstation mode:
CD (green led) on Instation modem board not lighting.
On test set RFE, IOR, SRM, BIR, RSE, RTE, CNL2, RCRC, RMSL.
POSSIBLE FAULT:
If ONLY any of the following faults are recorded when in Instation or Monitor
mode, Whilst UTC TCC/Instation see no faults with test set simulating the OTU,
i.e. in Outstation mode:
RMSL Reply not starting on time
BIR, RMS If OTU not replying with sufficient bytes
RCRC If OTU replying with too many reply bytes
POSSIBLE FAULT:
IF the test set is in Outstation mode and OTU faults are still being registered by
UTC TCC/Instation and no OTU faults are recorded by the test set when
simulating the Instation i.e. when in Instation mode, this indicates fault is with
Instation, e.g. numbers of reply bytes for OTUs incorrect, baud rate incorrect, 2/4
wire selection incorrect or full/half duplex selection incorrect, for the line.
666/HE/43100/000
TC12 Installation, Commissioning & Maintenance Handbook
Data corruption due to line or OTU, Now test at OTU.
When tested at OTU If no faults recorded when
simulating the Instation this would indicate that one of
the other OTUs on the line might be interfering with the
message. NB This can be checked from the Instation
end if it is allowable to switch all other OTUs on the line
off-line. Do this by going to the "TRANSMISSION
SYSTEM" screen and selecting CRCs to all other OTUs
except one under test to be incorrect. After
approximately four messages with the incorrect CRCs all
other OTUs will switch off line. If communications with
OTU under test are now error free then one of other
OTUs is interfering. NB OTUs will have logged the CRC
errors and will need fault log(s) clearing if they are to
remain accurate.
Minor incorrect timing / configuration in OTU. Now
test at OTU.
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