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The following symptom may be noticed in any AT6xxx shipped between February 1 and March 29, 2001. The units will contain serial numbers between 010201nnnnn and 010329nnnnn.

When using the 24V pull-up feature (when the IN-P pin or OUT-P pin on the AUX box is pulled up to 24V), the user will find that the inputs and outputs change incorrectly. The user may change one bit, and then find that more than one bit has been changed according to the TIN or TOUT command. The problem does not occur at lower pull-up voltages.

The error occurs due to an incorrect component assembled in the product. The vendor of this component provided us with the incorrect component.

Note: This problem will not affect performance, unless the 24V pull-up feature is used.

This cannot be fixed in the field, but it can be returned to Compumotor for a component replacement.