Rockwell Automation 57C419 5V-24V DC Input Module - Manual (Page 25)

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 3.4. Verify that the slot number being
referenced agrees with the slot number defined in the
configuration. Verify that the register number and bit
number are correct.
For remote I/O installations, also verify that the master slot
and 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 the DĆC power supply voltage (5Ć24 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 input circuit on the module is working
correctly.
Toggle the input device. Verify that the LED associated
with the particular bit is also toggling. If it is not, the input
module is malfunctioning.
Step 4. 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 I/O MONITOR is able to read the input, the problem
lies in the application software (proceed to step 5). If the
I/O MONITOR cannot read the inputs, the problem lies in
the hardware (proceed to step 6).
Step 5. Verify that the user application program is correct.
Verify that the application program that references the
symbolicnames assigned to the module has declared
those names COMMON in application tasks.
Verify that the symbolicname in question is being
referenced in the application program. This can be done