An interruption in communication between an I/O expansion module and controller can cause the controller to enter Stop Mode, and an ‘Expansion Error’ message to be displayed on the controller’s LCD.
This error results when:
The module was connected at power-up.
The communication between module and controller was interrupted for more than 200 milliseconds. Interruptions may occur if the connecting cables are disconnected, or may result from signal interference (noise).
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Note ♦ |
When a controller enters stop mode, the program stops running and all outputs within the system are initialized. This includes on-board outputs, outputs located on Snap-in I/O modules, and outputs located I/O expansion modules. |
What to do
Check that the cables are connected and in proper order.
Remedy signal interference. Such an error may also result from a hardware malfunction.
If the RUN LED on the expansion module blinks, check the documentation supplied with the expansion module to see if a hardware error is indicated.
To exit Stop Mode, reset the controller either by turning it off and on, or by entering Information Mode, and then selecting System>Working Mode> Reset.