Hitachi HSC-2100, Hardware Manual

Page: 156 / 169

6 MAINTENANCE
6-7
6.2.3 Troubleshooting a digital input module
z Case 1 -- none of the input points is turned on:
Check item Remedial action
Operation
indicator
LED
condition
Not
lit
Terminal block attached
improperly Attach the terminal block properly to the
module.
Module fixing-screws
loosened Apply additional tightening to the fixing
screws.
External power source not
supplying power Supply power from the external power
source.
Power supply module’s output
voltage abnormality Check the output voltage across the check
terminals of the power supply module.
External wiring incorrect Wire the module correctly.
Lit
Remote I/O station module’s
operation abnormality
Troubleshoot the remote I/O station
module according to the instructions given
in Subsection 6.2.2.
None of the above
Replace the digital input module with a
new one.
z Case 2 -- a particular input point(s) are not turned on:
Check item Remedial action
Operation
indicator
LED
condition
Not
lit
External input’s on-state
duration too short
Adjust the external equipment.
Wiring loosened or wire
breakage
Wire the digital input module correctly.
Lit Program I/O address error Corrent the erroneous address.
None of the above
Replace the digital input module with a
new one.
z Case 3 -- all of the input points are always turned on:
Check item Remedial action
Operation indicator LED not lit
Replace the digital input module with a
new one.
Operation indicator LED lit
Check the external wiring of the digital
input module for error.
If the wiring is correct, replace the module
with a new one.