Histogram in logix 500

[kevinprior 0]

Hi, We have recently put a histogram on a plc to monitor some inputs, we had this on for about an hour, when we came back the elapsed time had jumped up to about 48 hours, strange one this. The time in the plc status files is also running correct. has anybody seen this before? the other point is that we are having times when the DH+ network that this is connected to, locks up and loses all comms to the plcs, I feel that this may be related and this could be a faulty processor causing the network problems. Edited 12 Sep 2005 by kevinprior

[wwyatt 0]

Do you have terminating resistors on both ends of your network? If not you will get a lot of errors depending on the noise level.

[Guest]

I haven't seen your "jumping time" problem on the Histogram ... but then I hardly ever use it anymore ... it has a "dark side" when used with RSLogix500 ... (side note: the RSLogix5 version is much more usable) ... you might want to read this post particularly if the signals that you're trying to record are NOT very very slow ... basic idea: there are MUCH better ways of monitoring signals than the Histogram ... let us know if you need more detail ... case in point: I got called out once to help a plant troubleshoot a machine - and the technicians had been using the Histogram as their main "testing tool" ... they were getting nowhere ... as soon as I saw what they were doing, I turned the Histogram completely off ... I didn't really have to help them track down the problem ... they actually spotted it themselves in just a few minutes ... their biggest problem was that the Histogram wasn't showing them accurate indications - so they had been barking up the wrong trees for almost two days ... so ... if you can't trust your Histogram, then whom can you trust? ...