Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 60)

Chapter
7
Publication 1746Ć6.8 - April 1997
Module Diagnostics and
Troubleshooting
This chapter describes troubleshooting using the channel status
LEDs as well as the module status LED. It explains the types of
conditions that might cause an error to be reported and gives
suggestions on how to resolve the problem. Major topics include:
•
module operation vs. channel operation
•
power-up diagnostics
•
channel diagnostics
•
LED indicators
•
troubleshooting flowchart
•
replacement parts
•
contacting Allen-Bradley
The module performs operations at two levels:
•
module level operations
•
channel level operations
Module level operations include functions such as power-up
configuration and communication with the SLC processor.
Channel level operations describe channel-related functions, such as
data conversion and open-circuit detection.
Internal diagnostics are performed at both levels of operation and
any error conditions detected are immediately indicated by the
module’s LEDs.
At module powerup, a series of internal diagnostic tests is
performed. These diagnostic tests must be successfully completed or
a module error results and the module status LED remains off.
When a channel is enabled (bit 11 = 1), a diagnostic check is
performed to see that the channel has been properly configured. In
addition the channel is tested on every scan for configuration errors,
over-range, under-range, and, for the 4–20 mA input type,
open-circuit conditions.
Module Operation vs.
Channel Operation
PowerĆUp Diagnostics
Channel Diagnostics