4: TROUBLESHOOTING
SNAP-LCM4 User’s Guide
24
Digital output is not working. 1. Bad module fuse.
2. Wrong module type or
incorrect wiring.
1. Replace fuse.
2. Make sure module is 5V logic. Match the output
module with the load.
Digital input is not working.
1. Input device is not working
properly.
2. Wrong module type.
3. Voltage on input is not
compatible with module
voltage range.
4. I/O or brain may be bad.
1. Check input device wiring and power source.
Rewire, replace, or fix power source as needed.
2. Make sure module is 5V logic.
3. Change voltage to match module, or change
module to match field voltage.
4. See brain manual.
Analog output is not working. 1. Output is wired incorrectly.
2. Device is not properly
matched to module type.
3. I/O or brain may be bad.
1. Check wiring to output device.
2. Change voltage to match module or module to
match voltage.
3. Measure output with a multimeter.
Analog input is not working.
1. Voltage input device is wired
incorrectly.
2. Thermocouple has a break.
3. RTD has open or incorrect
wiring.
4. I/O or brain may be bad.
1. Check device and wiring. Connect voltage source
or current source, depending on input type, and use
multimeter to see whether input is functioning.
2. For a thermocouple, check for continuity across
test points next to module.
3. For an RTD input, check resistance across test
points next to module.
4. Contact Opto 22 Product Support if you find the
following:
–If value in software does not change with input
when testing input voltage or current with multimeter
–If thermocouple has continuity across test points
–If resistance across test points is about 100 ohms
for RTD input.
If you see this
It means
Try this
