Digital modules
8.4 SM 326; DI 8 x NAMUR
Fail-safe signal modules
122
Installation and Operating Manual, 01/2010, A5E00085586-10
Causes of the problem and corrective measures
The table below shows possible causes of the problem and appropriate corrective measures
for the individual diagnostic messages of SM 326, DI 8 x NAMUR.
Table 8- 15 Diagnostic messages and associated corrective measures for SM 326; DI 8 x NAMUR
Diagnostic message
Possible causes of the problem
Corrective measures
Interruption of the cable connection
between the module and NAMUR
sensor
Restore the cable connection
Contacts as sensors:
10 kΩ series resistance directly via
contact is missing or interrupted
Add 10 kΩ series resistance
directly via contact
Channel not connected (open)
Disable the "Group Diagnostics"
for the channel in the parameter
settings.
Wire break or internal fault
at the sensor supply
Internal sensor supply error
Replace the module
Short-circuit between
sensor signal and supply
lines
Short-circuit between the two sensor
signal lines
Eliminate the short-circuit
Process signal error
Defective NAMUR sensor
Check the process signal;
replace the NAMUR sensor
Short-circuit between the supply line
and the open signal line (open
contact) of the sensor
Eliminate the short-circuit
Wire break in connected sensor line
(contact closed) or the sensor supply
line
Eliminate the wire break
Discrepancy error
(1oo2 evaluation)
Assigned discrepancy time too short Check the discrepancy time
parameters
No external auxiliary
voltage
Module supply voltage L+ missing
Connect supply voltage L+
Module parameters not
assigned
No parameters transferred to module Assign new module parameters
Faulty parameters transferred to
module
Assign new module parameters
Incorrect module
parameters
Mismatch between the logical
module address set in
STEP 7
and
the address switch setting on the
module.
Adjust the address settings and
assign new parameters to the
module
Error in communication between the
CPU and the module, for example,
due to defective PROFIBUS
connection or electromagnetic
interference in excess of limits.
Check the PROFIBUS
connection
Eliminate the interference
Timeout of data frame monitoring
Check the monitoring time
parameters
CRC signature error, for example,
due to electromagnetic interference
in excess of limits.
Eliminate the interference
Communication error
CPU is in STOP
Read the diagnostics buffer
