FAQ No. FAQ03429
Why does the ERR signal come ON without displaying a Vision Sensor error message?
If a STEP signal (trigger to perform measurement) is input while the BUSY signal (indicates that it is processing the measurement) is ON, the ERR signal (error) comes ON and stays ON. If the STEP signal is input again after the BUSY signal has gone OFF, the ERR signal goes OFF and measurement is performed.
You can choose whether or not to turn ON the ERR signal in the System/Measurement Control options. The default setting is to turn ON the ERR signal.
This is applicable to all models subsequent to the F150 Vision Sensor.
These are the F150, F160, F180, F210, F250, F270, F400, and F500.