I am getting Bad quality reading from OPC server alarms

[Carl_Finley]

I am using RSLinx OEM talking to a DH485 network. Lookout is connected with OCP Client drivers. RSLinx DDE/OPC optimized packets monitor window is showing that I am getting 1 single bad packet every few minutes. Lookout immediately alarms. The alarm almost immediately clears and communications resumes. It is EXTREMELY annoying having Lookout alarm this often and needing to be acknowledged. One single bad packet certainly does not indicate a communications failure. There MUST be some way to induce a delay or something to prevent these constant false alarms.

[mrak1]

Hi,

I find it interesting that the OPC server is reporting this problem to the connected OPC client. In other OPC Servers that I have used, errors are not reported to connected clients until they have been verified or a retry has occurred. I would suggest contacting Rockwell to see if there is a way to configure your server not to report false errors. In Lookout's defense, it is just displaying what it receives.

[Khalid]

Hi Carl,

Here's how you can filter out these alarms: In the OPC CLient Object, set the Communication alarm to a lower priority, say 1. Then under Alarms>>Filter Options, check the Priority check-box and give 2 and 10 as Min and Max respectively.

This way you will filter out (all) alarms with a priority level of 1. Note that any other object that generates an alarm with Priority level of 1 will also get filtered by this, but you can make sure all others have a priority of no less than 2.

Hope this helps.

Regards,

Khalid

[Carl_Finley]

But then if you have and actual comm fail it will not alarm then either. This does not seem like a viable option. I was hoping a delay was somehow available. This would allow any nuicance alarm an opportunity to recover before alarming. Then if it did not recover within the delay period, it would alarm normally. Evidently Lookout has no such feature, but I think it would be something R&D could easily implement into maybe the next version of Lookout and it would be a very valuable tool.

[Khalid]

I agree that it will be nice if this "delayed alarm" feature was built in. Hopefully someday... Having said that, we can workaround the problem for now using my above suggestion and an Alarm object.

The above suggestion will filter out all comm alarams no doubt. A combination of Alarm object and the DelayOn object will let us view the genuine alarms. Create a DelayOn timer with the following configuration:

On/Off Signal = OPCclient1.CommFail
Timer delay = 0:05

And create an Alarm object which will alarm on this Timer, i.e.,

Condition = Timer1

This way, we filter out All comm alarms, but then look for any alarms which are active for 5 seconds (or whatever duration you wish) and then generate our o
wn alarm.

Hope this helps in the interim.

Khalid