A-B 1746-IM8 module Rockwell SLC 8 digital inputs

Module and Channel Diagnostics

The module operates at two levels.

• Module level

• Channel level

Module level operation includes functions such as cycling power, 

configuration, and communication with the SLC processor. ON 

indicates the module is OK. OFF indicates a fault.

Channel level operation includes functions such as data conversion 

and open-circuit detection. ON indicates the channel is OK. Blinking indicates a fault.

The module performs internal diagnostics at both levels, and 

immediately indicates detected error conditions with either of its status 

LED indicators. When a status LED indicator is continuously ON, the status is OK.

Module Diagnostics When Cycling Power

When you cycle the module’s power, the module performs a series of 

internal diagnostic tests. If the module detects a failure, its module 

status LED indicator remains off.Channel Diagnostics

When a channel is enabled, the module checks for a valid 

configuration. Then on each scan of its inputs, the module checks for 

out-of-range and open-circuit fault conditions of its inputs including the CJC thermistor.

When the module detects a failure of any channel diagnostic test, it 

causes the channel status LED indicator to blink and sets the 

corresponding channel fault bit (bits 12…15 of the channel status 

word). Channel fault bits and LED indicators are self-clearing when 

fault conditions are corrected.

IMPORTANT:If you clear the channel enable bit, channel status bits are reset.

Command Mode Operation All stepper motor operations are performed in command mode. 

This mode is entered by setting the mode flag (bit 15 in output word 0) to 0.

In command mode, the SLC Processor can issue commands and activate different operations or moves. The actions you can command are:

 • Absolute Moves

 • Relative Moves

 • Hold Moves

 • Resume Moves

 • Immediate Stop Operations

 • Homing Operations

 • Jogging Operations

 • Blend Moves

 • Preset Operations

 • Reset Errors

Diagnostic Mode

Use the configuration mode to select the diagnostic mode of operation. Once selected, 

the diagnostic mode allows you to test your program and wiring by connecting the loop back wires at the 

translator. The purpose of loop back diagnostics is to test the system wiring for electrical noise. 

The number of pulses received at the feedback should equal the commanded number of pulses at the end of the move. 

If they are not equal, the system may be experiencing problems due to electrical noise.

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