Rockwell Automation 1747-L40 SLC 500 Fixed Hardware Style - Manual (Page 78)

Chapter 6
Starting Up Your Control System
6–5
6. Observe the associated bit status using the programming device monitor
function. Also, observe the input status LED on the fixed I/O chassis.
A. When the input device is closed verify that the voltage at the input
terminal is within the specified on–state range, the input status LED is
on, and the associated status bit is set to a one.
If any of these conditions are not satisfied, follow the recommended
troubleshooting steps listed below.
B. When the input device is opened verify that the voltage at the input
terminal is within the specified off–state range, the input status LED is
off, and the associated status bit is reset to 0.
If any of these conditions are not satisfied, follow the recommended
troubleshooting steps listed below.
7. Select the next input device and repeat steps 5 and 6 until all inputs on the
fixed I/O chassis and in the 2–slot expansion rack (if used) have been
tested.
Input Troubleshooting Steps
1. Make sure the processor is in the Continuous Test mode.
2. Verify that your inputs and outputs are enabled. Status file bit S:11/0
represents the inputs and outputs of the fixed controller. Status file bits
S:11/1 and S:11/2 represent the inputs and outputs (slot 1 and slot 2
respectively) of the 2–slot expansion chassis. These bits must be set to
one, enabling all your inputs and outputs.
3. Check your wiring and verify that all connections are tight.
A. Make sure that power connections have been made to your input
device if needed.
B. Verify that the signal connection has been made from the input device
to the correct input circuit of the fixed controller.
C. Check that all common connections have been made.
4. Check your specifications.
A. Make sure that the power is within the specified voltage range if your
input device requires power.
B. Verify that your power supply is not overloaded. An overloaded
supply can deliver the correct voltage when some of its loads are not
energized but the voltage may fall out of range when all of its loads
are energized.
C. Verify that your input device signal contact is specified to deliver
sufficient current to the input circuit and any other loads connected to
it.
D. Make certain that your input device does not have a minimum load
specification that is greater than the input circuit current specification.
E. Verify that the input device is on and off longer than the specified
turn–on and turn–off times for the input circuit.