Omron NT31 Operation Manuals page 250

System Maintenance
- For a bar code reader
The check starts when the check screen is displayed. Read data with the bar
code reader in this status.
- If communication with the bar code reader is normal, the read character
strings are displayed in hexadecimal text code at "Received Data".
- If nothing is displayed at "Received Data" when data is read with the bar
code reader, there is a communication fault: check the communication
cables and settings.
S Check method
Check communication with the serial ports by following the menu operation from
the System Menu shown below.
Select "Maintenance Mode".
Select "I/O Check".
Section 6-11
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