Siemens SIMATIC S7 Functional Safety Manual page 126

Fail-Safe signal module (SM) diagnostics
6.2 Fault diagnostics
Event ID Diagnostic mes-
sage
0x004E PROFIsafe
communication
failure (timeout)
0x0100 Module is
defective
0x0103 Watchdog tripped
0x0105 Short-circuit to L+
0x0106 Short-circuit to
ground
0x0300 Discrepancy fail-
ure,
channel state 0/0
0x0301 Discrepancy fail-
ure,
channel state 0/1
126
Fail-safe signal Description
module
All Monitoring time ex-
ceeded for data
message frame
(timeout)
All Internal error
All The watchdog timer
in the SM communi-
cations processor
timed out.
SM 1226 F-DQ The fail-safe SM
4 x 24 VDC detects a channel
problem where the P-
terminal is unexpect-
edly at
L+ potential.
SM 1226 F-DQ The fail-safe SM
4 x 24 VDC detects a channel
problem where the
M-switch output
terminal is unexpect-
edly at M potential.
SM 1226 F-DI External discrepancy
16 x 24 VDC failure: Channel state
0/0 with 1oo2 non-
equivalent configura-
tion
SM 1226 F-DI External discrepancy
16 x 24 VDC failure: Channel state
0/1 with 1oo2 equiva-
lent configuration
Possible causes Corrective measures
F-monitoring time
•
exceeded
•
Fail-Safe SM is Replace the fail-safe SM.
defective.
Fail-Safe SM is Replace the fail-safe SM.
defective.
Short-circuit to L+ Eliminate the short-circuit.
Short-circuit be- Eliminate the short-circuit.
tween channels with
different signals
Defective output Replace the fail-safe SM.
driver
"Maximum readback Increase readback time.
time" value is con-
figured too small.
Short-circuit of out- Eliminate the short-circuit.
put to M, ground, or
another channel.
Defective output Replace the fail-safe SM.
driver
"Maximum readback Increase readback time.
time" value is con-
figured too small.
Process signal
• •
faulty, sensor
may be defec-
tive.
•
Configured dis-
•
crepancy time
•
too short
•
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
1
Adjust F-monitoring
time.
Check Safety program
and all other CPU activ-
ities for excessive exe-
cution or demands:
– Interrupts
– Ethernet communi-
cation
– OB scheduling con-
flicts
– Long program
paths.
Check process signal,
replace sensor if nec-
essary.
Check the configured
discrepancy time.
Check the wiring.
Check that both sen-