Why are my HI 1771WS status indicators flashing red after doing a C2® calibration?

When I try to do a C2® calibration my HI 1771WS module goes into calibration mode and sits there forever. The status lights Cal/Com on the module are flashing red and my block transfers are OK. I swapped the existing module with a spare and still no luck. Why are the status indicators flashing red after doing a C2® calibration?

Several checks should be done before a C2® calibration is attempted on the HI 1771WS module. The primary checks to make are:

1. Change the weight on the scale and see if the weight readings from the module change. These may not be correct weight readings, but the response is what is being checked.

2. Check for any error codes being sent from the module. These would be found in words 0, 1, and 2 of the block read. When using the configuration software with Rockwell's RS Logix 5, these can be checked on the "General" and "Calibration Status" screens. If there are errors present or if the weight does not respond, then the calibration would fail.

The flashing red cal/comm led would indicate the module is in calibration mode. If the calibration commands do not accomplish a calibration, then the bits to trigger the calibration may already be set. Since the module is looking for the leading edge of the change, if the bit is already on, it will be ignored. Check to insure that the Cal/Diag word, word 32 of the write data block, is set to zero before starting a calibration.

Once you have sent the module the calibration command, check the status words for any error responses indicating a pass or failure. Also, check to insure the Cal/Diag word, word 32 of the write data block, is set back to zero after the calibration is finished.