Run-Time Self Tests; Figure 1-13 Led Status During Normal Run-Time Operation - Siemens SIMATIC TI505 User Manual

Run-time Self Tests

SIMATIC TI505/TI500 MODNIM User Manual
The MODNIM monitors itself continuously during normal operation as
follows.
The operating system continuously performs a ROM integrity test as a
background process.
The MODNIM periodically verifies that it is capable of communicating
with the PLC.
A Watchdog Timer circuit in the MODNIM guards against software
lockup.
If any failures are detected in the ROM integrity test, the NIM GOOD
indicator light turns off and the MODNIM is forced into the failed state. In
this condition, the module goes into the Offline Mode and will not respond to
any requests. (See Figure 1-13.)
When the MODNIM is in its normal operating mode but fails to
communicate with the PLC, it reports this failure to the host computer with
an exception response. Error code 04 (failure in associated device) is sent,
and the PC GOOD (PC/NIM COMM GOOD) indicator goes out. (See
Figure 1-13.) If communication is re-established, the MODNIM returns to
normal mode and the PC GOOD indicator goes back on.
NOTE: The first time a valid request is received, the ON LINE indicator
goes on and remains on as long as everything is operating properly.
NIM PC
GOOD GOOD
XMT REC
ON
LINE TEST
All Run-time
tests OK

Figure 1-13 LED Status during Normal Run-Time Operation

The Watchdog Timer circuit provides an extra measure of protection against
network lockup due to a failed MODNIM. This circuit will force a RESET if
the operating software fails to execute normally.
NIM PC
GOOD GOOD
XMT REC
ON
LINE TEST
ROM Integrity Failure:
goes to Offline Mode
Installation and Set-up
NIM PC
GOOD GOOD
XMT REC
ON
LINE TEST
Not Communicating with
PLC: reports Error Code 04
1-17