Rockwell-automation 1746-NI8 SLC 500 Analog Input Modules User Manual Manual de usuario descargar pdf (Pagina 60)

Chapter 7

Publication

17466.8 - 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

PowerUp Diagnostics

Channel Diagnostics

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Rockwell-automation 1746-NI8 SLC 500 Analog Input Modules User Manual Manual de usuario Pagina 60