Rockwell Automation 57C400-1 115V AC/DC Input Module - Manual (Page 19)

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. For this module, the register number is
always zero. Verify that the bit number refers to the proper
bit. Note that the bit number and the wire number are not
the same.
For remote I/O installations, also verify that the master slot
and remote drop number are defined correctly.
Step 2. Verify that the input is wired to the correct device.
Confirm that all connections at the terminal strip are tight.
Connect a voltmeter to the proper points on the terminal
strip and toggle the device. The voltmeter should alternate
between 0 and 115 volts. If this does not happen, there is
a problem with either the external device, the DĆC power
supply, or the wiring to the terminal strip.
Check the cable for continuity between the faceplate
connector and the terminal strip.
Step 3. 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.
Toggle the input device to determine whether the bit is
changing state.
If the programmer is able to read the input, the problem is
in the application software (proceed to step 4). If the
programmer cannot read the inputs, the problem is in the
hardware (proceed to step 5).
Step 4. Verify that the user application program is correct.
Verify that the application program that references the
symbolic names associated with the module has declared
those name COMMON in application tasks.
Verify that the symbolic name in question is being
referenced in the application program. This can be done
indirectly by monitoring the name with the VARIABLE
MONITOR function in the ReSource Software.