I have issue with Porcheson plc. Initially it was running well. Upon closing the doors of a machine it confirms safety door closed ,after two seconds a “door fault ” alarm comes and all operations are terminated. Initially i suspected HMI could be the problem. I brought in a newHMI and fixed. The same alarm came in. What could be the cause of this ?
Hi Jonah and welcome to the forums! Admittedly I’m not familiar with this line of PLC’s, however, to me it sounds more like an internal logic problem or possibly a door hardware/feedback (possibly intermittent) problem. You will need to look at the logic to see what exactly is causing the alarm to trigger. If available in this software, what I would do is setup a trend or some kind of monitoring to see what exactly is causing this fault. Is there an actual delay timer on the fault (you did mention 2 seconds) or is it latching in right away based on the feedback from the doors closed inputs? Obviously lots of things to check and difficult to tell based on the information you’ve provided.
If you have a safety relay monitoring this door (which you should have with a forced guided relay) and you are operating at 24VDC, use a good multimeter (Fluke 87) and check for a voltage drop to the PLC input. The meter can be set up to record minimum and maximum values. If there is no voltage drop, replace input module. Most 24VDC input modules have a threshold of 18VDC to turn on or off. If there is a voltage drop after 2 secs, (below 18VDC) for an instance, check your DC Power supply with a scope for line noise or other equipment interfering.