Siemens SIMATIC S7 Equipment Manual page 33

Data communica-
tion, program run
time and supply
voltage
Memory error
SM 338 Equipment Manual
(4) J31069-D401-U1-A0-7618
7
Byte 2 0 0 0 0
Time monitoring
The module is equipped with a time monitoring function to check that the
firmware is functioning correctly. If program run time exceeds a certain time
frame, a RESET is triggered on the module. The module then boots with the
default parameters and does not go into an undefined state.
7
Byte 3 0 0 0 0
When a memory error occurs, the module can only be started again with a
RESET on the bus.
Data Communication with the PLC
0
0
Communication malfunction
(detected by the module)
Time monitoring
(Watchdog has triggered a RESET.)
Failure of internal module supply
voltage
(sensor supply +15 V/+24 V; inter-
face supply 5 V)
0
0 0
EPROM error
(wrong checksum during test)
RAM error
4-11