Siemens SIMATIC S7 - Hardware Troubleshooting Guide

Debugging and troubleshooting
10.7 Hardware troubleshooting guide
S7-200 SMART
578 System Manual, V2.3, 07/2017, A5E03822230-AF
10.7
Hardware troubleshooting guide
Table 10- 1 Troubleshooting guide for the S7-200 SMART hardware
Symptom
Possible cause
Possible solution
Outputs stop working The device being controlled has
caused an electrical surge that dam-
aged the output
When connecting to an inductive load
(such as a motor or relay), a proper
suppression circuit should be used.
Refer to
the wiring guidelines in Chap-
ter 3.
Wiring loose or incorrect
Check wiring and correct
Excessive load
Check load against contact ratings
Output point is forced
Check the CPU for forced I/O
ERROR light on the CPU turns on
(Red)
Electrical noise Refer to the wiring guidelines in Chap-
ter 3. It is very important that the con-
trol panel is connected to a good
ground and that high voltage wiring is
not run in parallel with low voltage
wiring.
Connect the M terminal on the 24 V DC
Sensor Power Supply to ground
Component damage Send in hardware for repair or re-
placement
None of the CPU LEDs turn on Blown fuse Use a line analyzer and monitor the
input power to check the magnitude
and duration of the over-voltage spikes.
Based on this information, add the
proper type surge arrestor device to
your power wiring.
Reversed 24 V power wires
Refer to the wiring guidelines in Chap-
ter 3 for information about installing the
field wiring.
Incorrect voltage
Intermittent operation associated with
high energy devices
Improper grounding Refer to the wiring guidelines in Chap-
ter 3.
Routing of wiring within the control
cabinet
It is very important that the control
panel is connected to a good ground
and that high voltage wiring is not run
in parallel with low voltage wiring.
Connect the M terminal on the 24 V DC
Sensor Power Supply to ground.
Time delay on input filters too short Increase the input filter delay in the
system data block.