Fault PLC5/40

[Angel David 1]

Hi there i have a trouble and i can't find where is the origin of trouble. My problem reside in one PLC5/40, this device have 15 years about working without troubles, suddenly about 6 months ago he start with a random failure which i can resolve with some tricks however this its not have apparent cause. the first trouble i had was the equipment lost communication intermittently, i resolve this changing the wire between the PLC and the Panelview but i tested the wire and its ok. later the equipment go to fault because one timer preset it was written in negative, i corrected this placing in logic the consideration of, it was negative dont write, however this thing never happen in 15 years. later the equipment go to fault because one counter preset it was written in negative, i corrected this placing in logic the consideration of it was negative dont write, however this thing never happen in 15 years. I think this failure its because the equipmente its broken, but i can't find any paper or technical document where indicate this failure its a hardware failure if you know where its the trouble about or where find a technical answer i won't be able to thanks enough. Thanks for your time guys !

[Mickey 71]

Counter presets CAN be negative. This would not fault your processor. Edited 26 May 2014 by Mickey