Pre-warnings in RSView or RSLogix?

[RayK]

We have warning in RSview that tell of rates getting to high for the pumps to cope, but they are set up so that when the warnings go off its to late to do anything about it and the pumps are bogged. so the operators have asked if they can have a "pre-warning" setup that go off say 50kilos before the main warnings,in addition to the warnings as set up, my question is, is it better to do this in RSView with more tags and expressions or in RSLogix with more ADD SUB and LIM ?

 

[tom_stalcup]

Ummm... Probably both will be needed, depending on how your current setup is.
I guess the answer to that is going to depend on what you are going to do differently in the process when you get an "alarm" instead of a "pre-alarm". When you get an alarm, does the process automatically shutdown, or does any other action take place?

 

[RayK]

Yes the alarm sounds and it shuts down the Main pump to Feed Cyclone, the guys say another different sounding siren and a flashing red light on the main page in RSView would be ideal. I suppose it could be done either way, so was just wondering which way would be considered "normal". thou doing it in RSlogix would add to the scan time? (its at 2x 10ms)

 

[tom_stalcup]

I'd like to be able to say what to do "normally", but I don't that wide of a base to talk from.

The way the hmi's at my plant are set up(by someone else), the calculations for alarm triggers are done in the plc code(using lim's, etc), and then the alarm tag will be triggered in the hmi based on the state of the bit in the plc. There may in fact be a way to do this wholly from the HMI, but i'm afraid I don't know how to do it. Do you know how the current alarms are setup/triggered? The easiest way would probably be to copy the current setup, to keep everything consistent.

As far as the scan time is concerned, how many pumps are you looking at adding extra alarms for? And what specific plc are you using?

 

[Gerry]

If the "kilos" is monitored as an analogue tag in RSView, then it's a simple matter to set up alarm thresholds within RSView. An analogue tag can have 8 alarm thresholds which can be set to trigger as the value either increases or decreases through the threshold.

 

[RayK]

Yes Tom our plant is set up similar to what you describe, with the SCL setting the values in the N7 registers and then the LIM setting the B3 bits on or off, they need the pre-alarms set on 9 pumps at this stage to indicate either flow (SG) or TPH. I was half way through setting up the pre-alarms in RSlogix (about 18 rungs) when I figured maybe it could be done in RSView, thou I have yet to learn RSView I will look into what Gerry Suggested. So many thanx for the pointers