Can anybody help me with a problem i am encountering with a machine equiped with amicrologix 1000 plc. The processor occasioally indicates a fault (flashing red led) and all outputs are dissabled. When i connect the laptop and select 'goto error' from the status toolbar, a message reads 'Retentative data lost' and also flags a fault S:1/13 & S:5/8. If I reset these and put the processor back into run mode it works fine for about a day then the same fault appears. Does anypne know what may cause this. My plc knowledge is quite minimal so please don't be too technical. cheers

MicroLogix are very sensitive to electrical noise/poor power quality. Ensure that the ML1000 is connected to a good solid ground via AWG14 ground wire. You might want to put a TVSS/Noise suppressor on the power feeding the ML1000 as well, unless you are sure you have good, stable power from something like a constant-voltage transformer. Also, if any of you outputs are controlling inductive loads (coils, solenoids, etc.), install surge suppressors across the outputs in accordance with the ML1000 user manual.

Have a look at AB Knowledge Base tech note E19443 - MicroLogix 1000 faults with S:6 = 0005h, Retentive Data Has Been Lost

QUOTE

The Major Error Code, S:6 = 0005h can occur after an error of S:6 = 0002h and can be caused by noise. If the controller has a 24vdc user power supply, a short on the wiring to the supply can also cause this.

If this is a 24 VDC powered unit I would look at the power supply first but it seem everything I can find points to noise.

Edit - Mgvol beat me to it and did a much better job of explaining it but I'll leave this one. You may want to read the tech note too. Nice response time mgvol

Cheers guys, you both seem to have hit on the same cause. The unit is in a foundry environment and is subject to both inductive noise & metalic dust, so your diagnosis looks bang on, i'll get onto it as soon as possible. Thanks for your help

Yea foundries are very CLEAN environments. You can duct tape the around the door seal of a panel so it won't open and still get that dust on everything inside.