False outputs

chevysrockz24

Hi everyone.  I am working with a ABB 1400 M98 and controlling two servo motors for positioning weld fixtures.  Each servo has 4 positions 90 degrees apart.  These are commanded by using outputs from the robot's controller to the servo drive.  One output for each position on each servo so 8 outputs in total.  Once yesterday and once the day before, the servo rotated without any command.  Once on each servo and a different position on each. However, on the teach pendant i/o screen, none of these outputs were on.  Has anyone had a similar problem?  Is there any way that the i/o board(328 i believe) could malfunction and quickly send a signal out?  As far as I can tell its not a wiring issue.  Thanks.

graemepaulin

I have not heard of outputs malfunctioning and going high randomly (only not working at all).

This being a welding cell using a shielded control cable, ensuring the shield is correctly earthed , and if possible running the control cable away from any welding cables (power or earth return) would be the place to start.

Often induced noise in control cables causes issues.