Rockwell Automation 1746-HSCE,D17466.5 High-Speed Counter Module - Manual (Page 111)

Publication 1746-UM006B-EN-P - August 2005
Start-Up, Operation, and Troubleshooting 5-5
Rate Measurement Overflow
When the Rate Measurement exceeds 32,767 Hz, the Rate
Measurement overflow bit (I:e.0/5) is set to 1. The module will
continue to run the rate measurement calculation and will clear the
error if the input frequency drops below 32,767 Hz. If operating in the
Rate Mode, the module controlled outputs are reset to 0 while this
error is present. Outputs controlled from the user program are not
affected.
Counter Value Does Not Change
Check the module LEDs for channel A and B inputs with pulses
coming in. The A and B LEDs should illuminate regardless of the
software configuration of the High-Speed Counter module.
If the A and B LEDs are not illuminated, check the power to the input
sensor, and the wiring from the sensor to the module.
If the A and B LEDs are illuminated, make sure that configuration of
the module is complete and that the Function Control bit has been set
to 1 by your program. Also make sure the Counter Hold bit has not
been set.
If input channel will not turn off, check the leakage current of the
input sensor (refer to Max Off-State Leakage Current on page A-1).
Counter Value/Rate Goes in the Wrong Direction
If differential quadrature encoder inputs are used, swap channels A
and B to change the direction.
If pulse and direction inputs are used, check the Direction and Input
Type (M0:e.1/3 and M0:e.1/9-11).
If using up/down count mode, make sure Inputs A and B have not
been switched.
IMPORTANT
When this bit is set, the Rate Measurement Overflow
bit (I:e.0/5) is set.