Content Summary
This tech note guides customers using a PLC with mechanical relays and discrete I/O to apply a low pass filter on Checker inputs. This aims to eliminate noise from the relays. Symptoms of noise include intermittent job change failures, where the selected job is incorrect or does not appear to work, often defaulting to a higher numbered slot. Additionally, unexpected retrain or trigger events may occur, indicating the need for noise reduction.
For customers using a PLC with mechanical relays and communicating with discrete I/O to the Checker. This tech note explains how to implement a low pass filter for your Checker to eliminate noise on the Checker inputs caused by the relays.
Symptoms
-Job change does not appear to work or the selected job isn't the job that was requested. Typically, this is an intermittent problem, sometimes it works but often it doesn't. Typically, the selected job is a job in a higher numbered slot.
-The Checker retrain or trigger doesn't occur as expected. Sometimes extra retrain or trigger events occur.
Symptoms
-Job change does not appear to work or the selected job isn't the job that was requested. Typically, this is an intermittent problem, sometimes it works but often it doesn't. Typically, the selected job is a job in a higher numbered slot.
-The Checker retrain or trigger doesn't occur as expected. Sometimes extra retrain or trigger events occur.