Rockwell Automation 61C346 4 Input 0-10V Analog Rail Module - Manual (Page 38)

5Ć4
Step 1. Verify that the application program(s) is correct. Check to
see that the program is referencing the correct registers
(AutoMate) or symbolic names (DCS 5000/AutoMax).
In DCS 5000/AutoMax applications, make certain that the
program is not attempting to write to the input channels.
Step 2. Stop any application tasks that are running. Turn off power
to the Analog Rail module.
Step 3. Try to clear the condition by disconnecting and then
reĆconnecting the I/O Rail cable. Make certain the
connections are tight. If applicable, check the connections
between the host and the Local I/O Head, the AutoMate
Remote I/O Head, or the DCS 5000/AutoMax Remote I/O
Head. Check that the input connector pins are not bent.
Step 4. Turn off power to the external hardware. Verify that the
wiring to the external hardware is tight and functioning
correctly.
Step 5. Turn on power to the external hardware.
Use the Executive software to read the value on the input
channels. Use a voltmeter to read the input signal and
compare the two. If the signal is being converted correctly,
there is a problem with the external hardware or wiring.
Step 6. Troubleshoot the external hardware, the wiring, and the
host.
5.4 Constant UnderĆRange
Problem: the underĆrange bit (12 decimal) on an input channel
register is constantly set to 1. Assuming that the power supply for the
external hardware connected to the input channels is providing an
input signal within the specified limits (0-10V), the possible causes
of this problem are incorrect (reversed) input signal wiring on the
module faceplate, a loose connector on the analog section of the
faceplate, or loose or malfunctioning wiring. Follow the steps below
to isolate the problem.
Step 1.
Stop any application tasks that are running. Turn off power
to the external hardware connected to the module. Turn
off input power (120 VAC or 24 VDC) to the module.
Step 2. Verify that the 12Ćpoint connector on the analog section of
the module faceplate is securely attached to its mating
half.
Step 3. Verify that the signal wiring on the module faceplate is
correct. See step 9 in section 3.2 for more information.
Verify that the wiring is tight and functioning properly.