Rockwell Automation 57C409 2 Channel Analog Input Module - Manual (Page 27)

5Ć1
5.0 DIAGNOSTICS AND
TROUBLESHOOTING
This section explains how to troubleshoot the module and field
connections.
5.1 Incorrect Data
Problem: The data is either always off, always on, or different than
expected. The possible causes of this are a module in the wrong slot,
a programming error, or a malfunctioning module. It is also possible
that the input is either not wired or wired to the wrong device. Use the
following procedure to isolate the problem:
Step 1.
Verify that the input module is in the correct slot and that
the I/O definitions are correct.
Refer to figure 3.2. Verify that the slot number being
referenced agrees with the slot number defined in the
configuration task. Verify that the register number and the
bit number are correct.
Step 2. Verify that the module can be accessed.
Connect the programming terminal to the system and run
the ReSource Software. Use the I/O MONITOR function to
display the eleven registers on the input module.
Step 3. Verify that the user application program is correct.
Verify the application program has defined as COMMON
any symbolic names associated with the module.
Verify that an update period has been written to registers 7
and 8. Remember that each count is .0005 seconds (500
mseconds). This value specifies the frequency with which
the analog values will be converted to digital numbers.
Verify that common clock has been turned on. The
uppermost LED on the faceplate of the module should be
lit. If common clock is not present on the backplane, the
module will not convert the analog inputs to digital values.
If common clock is originating from this module,
remember that bit 6 in registers 5 and 6 must be set.
Verify that the input filters in registers 9 and 10 have been
set to the proper values for the signals connected to the
module. If the filter values are set too low, the filters will
remove useful signal information. If they are set too high,
the module may convert noise instead of the actual signal.
Step 4. Verify that the input is wired to the correct device.
Verify that all connections at the terminal strip are tight.
Refer to figure 3.1 for typical field connections and
Appendix C for terminal strip connections. Make sure that
each input channel is wired to the correct field device.
Connect a voltmeter to the proper points on the terminal
strip and confirm that the external device is generating the
correct voltage or current.
Check the cable continuity between the faceplate and the
terminal strip.