Siemens SIMATIC S7 Functional Safety Manual page 128

Fail-Safe signal module (SM) diagnostics
6.2 Fault diagnostics
Event ID Diagnostic mes-
sage
0x0313 Failure in the input
circuit
0x0316 Relay cannot be
turned on
0x0317 Relay cannot be
turned off
(contacts welded)
0x031C Input shorted to P
0x031D Output defective
0x031E Read back failure
128
Fail-safe signal Description
module
SM 1226 F-DI Internal fault at the
16 x 24 VDC read circuit/test cir-
cuit
SM 1226 F-DQ Relay activated, but
2 x Relay remains deactivated
SM 1226 F-DQ Relay deactivated,
2 x Relay but remains activated
(Relay contact is
welded)
SM 1226 F-DI Input shorted to P
16 x 24 VDC failure
SM 1226 F-DQ Relay coil driver
2 x Relay defective
SM 1226 F-DQ The SM has detected
4 x 24 VDC a channel problem
where the expected
terminal voltage(s)
are not reached.
Possible causes Corrective measures
The input SM de-
•
tects a failure during
bit pattern testing of
inputs. EMI or SM
hardware fault.
•
Relay is faulty. SM
•
supply voltage too
low.
•
Relay is faulty, due
•
to normal wear,
excessive load, or
•
unsuppressed in-
ductive load.
•
•
External wiring or Check/correct external
sensor shorts input short-circuit.
signal to L+.
Input configured for Make wiring and configura-
short-circuit detec- tion agree.
tion but wired to
external L+
Input defective Replace the fail-safe SM.
Relay or relay driver Replace the fail-safe SM.
faulty
"Maximum readback Increase readback time.
time" or "Maximum
readback time
switch on test" con-
figured value is too
small.
Output switch fail- Replace the fail-safe SM if
ure output does not respond.
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
1
If intermittant, probably
due
to interfer-
ence. Eliminate inter-
ference.
If persistent,
or repeats after efforts
to
eliminate interference,
replace the fail-safe
SM.
Check for supply volt-
age warning messages
and supply voltage.
Replace the fail-safe
SM.
Replace the fail-safe
SM.
Check that load current,
including inrush, is with-
in specifications.
Check for adequate
inductive load suppres-
sion and capacitive
load inrush limiting.
Check for circuit faults
creating excessive
load.