Hardware reference guide

Modbus Plus NOMs
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LED Indicators and Descriptions
The following figure shows the Modbus Plus NOM LED indicators.
The following table shows the Modbus Plus NOM LED Descriptions.
LED Error Codes
The blinking Run LED error codes for the NOM module shows the number of times
the Run LED on the NOM module blinks for each type of error and the crash codes
for each (all codes are in hex).
LED Descriptions
LEDs Color Indication when On
Ready Green The module has passed power-up diagnostics.
Run Green Indicates that the unit is in kernel mode–should always be OFF
during normal operations.
Modbus Green Indicates communication is active on the single RS-232 serial port.
Modbus+ Green Indicates communication is active on the Modbus Plus port.
Error A Red There is an error condition on Cable A of a dual cable Modbus Plus
network (140NOM21200 only).
Error B Red There is an error condition on Cable B of a dual cable Modbus Plus
network (140NOM21200 only).
LED Error Codes
Number of Blinks Code Error
Steady 014H normal power down event
2 815 ram sequence error
3 49H illegal data command received by bypass code
4BH diagnostics test pattern invalid in the icb block
4CH diagnostics test pattern invalid in the page 0
4DH icb address not the same as found in hcb