User manual

Publication 1747-IN011F-EN-P - May 2007
166 Troubleshooting
Troubleshooting Your Input Modules
If your input
circuit status
indicator is
And your input
device is
And Probable Cause Recommended Action
On On/closed/activated Your input device will not
turn off.
Device is shorted or
damaged.
Verify device operation. Replace
device.
Your program operates as
though it is off.
Input circuit is
damaged.
Verify proper wiring. Try other input
circuit. Replace module.
Input is forced off in
program.
Check the FORCED I/O or FORCE
status indicator on processor and
remove forces.
Off/open/deactivated Your program operates as
though it is on and/or the
input circuit will not turn off.
Input device Off-state
leakage current
exceeds input circuit
specification.
Check device and input circuit
specifications. Use load resistor to
bleed-off current.
Input device is shorted
or damaged.
Verify device operation. Replace
device.
Input circuit is
damaged.
Verify proper wiring. Try other input
circuit. Replace module.
Off On/closed/activated Your program operates as
though it is off and/or the
input circuit will not turn on.
Input circuit is
incompatible.
Check specification and sink/source
compatibility (if dc input).
Low voltage across the
input.
Check the voltage across input circuit
and check source voltage.
Incorrect wiring or an
open circuit.
Check wiring and COMmon
connections.
Input signal turn-on
time too fast for input
circuit.
Check timing specifications.
Input circuit is
damaged.
Verify proper wiring. Try other input
circuit. Replace module.
Off/open/deactivated Your input device will not
turn on.
Input device is shorted
or damaged.
Verify operation. Replace device.
Your program operates as
though it is on.
Input is forced on in
program.
Check processor FORCED I/O or
FORCE status indicator and remove
forces. Verify proper wiring. Try other
input circuit. Replace module.
Input circuit is
damaged.
Verify proper wiring. Try other input
circuit. Replace module.