Can a PLC do Sequence of Events?
Can a PLC do Sequence of Events?
(OP)
We are looking to put in a SCADA system on our power system. We contracted a place to give us a proposal and they recommended we wire the alarms from the field to an annunciator panel that will provide the Sequence of Events snapshots. From there the same points on the annunciators will wire to a PLC to provide constant monitoring.
And we have to get this fiber optic gizmo to provide a sychronous clock signal into each annunciator and PLC.
I mostly understand the reasoning and function of each part but wonder why a PLC couldn't just do it all?
And we have to get this fiber optic gizmo to provide a sychronous clock signal into each annunciator and PLC.
I mostly understand the reasoning and function of each part but wonder why a PLC couldn't just do it all?





RE: Can a PLC do Sequence of Events?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Can a PLC do Sequence of Events?
RE: Can a PLC do Sequence of Events?
RE: Can a PLC do Sequence of Events?
I saw something on that online on that, and in part prompted my question. That resolution is the same as the annunciator.
Don't you think it would make more sense to just wire directly into the PLC instead of going first to a remote annunciator? But there is an existing annuciator with all the wires right there....but we could just re-use it and output to it from the PLC....
And too this setup is multiplied by about 50 throughout our site spaced from nearest to farthest about 1500 feet. The sychronization is important which is provided by a satellite signal. Do PLCs also have these synchronization modules that could daisy chain from PLC to PLC?
I can see the scenario where the info available at the 1500 foot away PLC is part of the sequence of events that prompted an annunciation at the 5 feet away PLC.
RE: Can a PLC do Sequence of Events?
to answer my own question it looks like the AB will do 100 mS resolution, the annunciator that has been proposed is 4mS. Looks like AB has some work to do if they want to compete in that market.
RE: Can a PLC do Sequence of Events?
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If we learn from our mistakes I'm getting a great education!
RE: Can a PLC do Sequence of Events?
I guess that means we can beat the 80's after all Scotty. Still cant beat the 60's and early 70's for music though...
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Can a PLC do Sequence of Events?
After reading further on the annunciator, its resolution
is 50 mS standard down to 1mS if you want to pay for it. I'd link to the page but you have to have a password to get to it. There is nothing mentioned about uS.
AB wins after all....in a landslide.
Now back to my original question. If the PLC can do all the I/O, the SOE, why can't it also do the synch clock function too?
RE: Can a PLC do Sequence of Events?
RE: Can a PLC do Sequence of Events?
"Simple Global Positioning Satellite (GPS) integration using HiProm's 1756-HPGPS module allows geographically separate systems to operate with the same correlated time values."
Cut sheet here:
http
I've never had to do anything like this, but it looks like an interesting app.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Can a PLC do Sequence of Events?
I guess you would stick one of these into each one of your PLCs? There is no need to daisy chain a clock signal from one PLC to another....? That's how I take it.
As you called it earlier this is third party too. I guess that is common in PLC world and is perfectly fine?
RE: Can a PLC do Sequence of Events?
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Can a PLC do Sequence of Events?
RE: Can a PLC do Sequence of Events?
Many of the annunciated points are wired to a control relay contact that is activated by as many 10 different field devices on one production line. So an alarm could mean 10 different things, then the fun begins. I know this sounds primative but when you are talking literally 1000's of devices its not easy to upgrade without spending gazillions of dollars.
But since all the wiring is already coming into these control relays it seems easy enough to replace the control relays with a terminal strip, wire the devices directly into into the SOE cards in the PLC, link all the PLCs together and voila I've got full status of the system and have full SOE. Am I oversimplifying this? Is there limitations in computing power of PLCs to do such a thing?
RE: Can a PLC do Sequence of Events?
RE: Can a PLC do Sequence of Events?
I think you can probably do the SOE on remote racks, but I think it would be worthwhile to have the ab guys come in to talk with you concerning your project. I think you have narrowed down what you want to do and now you need to get them in and grill them about what this card can really do. I would think they would jump at this chance.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Can a PLC do Sequence of Events?
He did mention that they would recommend a CIP Synch module, that is either fiber or copper to get the GPS signal...the GPS module you found may be a better option there. Any experience with CIP Synch?
All this to me is but one option of three. The consultants plan another and the third....
An integrated system made by Schwietzer Engineering Labs exclusively for SCADA systems. From what I understand SEL has the market on SCADA in the utility world. However I can see the advantage of using A/B because everything else in the plant is A/B and many people know how to work on them.
Thanks PLCMentor and djs for the help.
RE: Can a PLC do Sequence of Events?
As far as the help goes, this was interesting for me also. Feel free to contact me if you need to discuss this more freely. I think we have taken this to the extent a forum can cover a subject.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Can a PLC do Sequence of Events?
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If we learn from our mistakes I'm getting a great education!