Hardware Troubleshooting Guide - Siemens SIMATIC S7 System Manual

Debugging and troubleshooting

10.7 Hardware troubleshooting guide

10.7 Hardware troubleshooting guide
Table 10- 1 Troubleshooting guide for the S7-200 SMART hardware
Symptom
Outputs stop working
ERROR light on the CPU turns on
(Red)
None of the CPU LEDs turn on
Intermittent operation associated with
high energy devices
578
Possible cause
The device being controlled has
caused an electrical surge that dam-
aged the output
Wiring loose or incorrect
Excessive load
Output point is forced
Electrical noise
Component damage
Blown fuse
Reversed 24 V power wires
Incorrect voltage
Improper grounding
Routing of wiring within the control
cabinet
Time delay on input filters too short
Possible solution
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.
Check wiring and correct
Check load against contact ratings
Check the CPU for forced I/O
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
Send in hardware for repair or re-
placement
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.
Refer to the wiring guidelines in Chap-
ter 3 for information about installing the
field wiring.
Refer to the wiring guidelines in Chap-
ter 3.
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.
Increase the input filter delay in the
system data block.
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART