plc/hmi comm. issue

We have a piece of machinery that uses a GE 90-30 rack system. It communicates to a pc with a touchscreen running Cimplicity via Ethernet. The HMI has been running flawlessy for quite some time now ( years) and have recently noticed that every once in awhile the screen graphics turn to black ( Like it isn't communicating) then everything ( data) will pop back a few secods later. I am wondering what would cause this, at first i am leaning towards maybe the cable is bad, so i may start there. Any other suggestions. Thanks

Hi jcraft

This is probably a stupid suggestion but are you sure it isn't that nothing is happening for a while and the screensaver is kicking in??

If not, then I would suggest checking the cable too.

Is it always "black" for the same amount of time?
Are there any other issues when it comes back from one of its 'blackouts'?
It might also be worth making sure there isn't a build of dust and **** inside the screen causing over-heating issues?

Cheers

;-)

The entire screen isn't going black, basically the entire graphics screen is shown it's just the data associated with the graphics is blacked out and not showing the values or some show xxx

Well that normally means that either the address that is trying to be read isn't there/is out of range OR you've lost comms (as you suspected).

So... you were right. Check the cable and connections both sides.

Also be wary of 'noise' causing interference.

I'm assuming that nothing has recently changed with the installation (i.e. have you added any new motors / mains wiring etc)?