analogue output comms failure -timeout problem

manjit

Guest
M
Dear all,
I am using allen bradley plc 5/20 alongwith scada system of qnx windows as OS.when I am swiching on the power to the plc and pc (which contains the qnx software),it is continously showing the error of "analogue output comms. failure -timeout".I do not have a laptop to chk the plc program also.

can someone pls enlighten me as to what could be the possible causes of this problem?
manjit.
 
Hi Manjit,

It could be that whenever you boot up the plc looses some values,i.e you may have to condition a block transfer with S:1/15 (first scan of ladder or sfc)so as whenever you power up some data is written to your analogue output card.try this as i don't know much about the other hmi softare you are using.
 
That's a tough one. First, you need to find out what the heck triggers thr error message. You might find that on the PC if you have the development package for the software resident on the PC. Then when you find out what in the PLC triggers the errror message, if you've got a printout of the ladder, you might find the problem. But, I have found in the past, for the most part (99.99%), that PLC systems without programming terminals are unsupportable when you start getting "strange" faults. And another thing, anyone who expects you to support such a system without a programming tool has his head so far up his own arse, he will probably never see the light of day again.
 
r u right john

Dear john,
I guess u r right .I have trying to check out the problem thru the qnx scada software but i am also ne to the software and so till date have been unable to crack how the alarms have been set in the qnx software.also there is another point i.e when i switch off the plc ,the alarm still repeats ,so i feel that the error message must be generated from the qnx scada system itself and has nothing to do with the plc analogue outputs configured.
If anyone can throw some more light on my prob. pls feel free to vent urself ,as i might get a clue from it.
Thanks everybody
manjit
 

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