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| 1/18/2013 10:56 PM | |
Joined: 3/14/2008 Last visit: 11/5/2024 Posts: 2122 Rating:
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Hello, using a SFC type in 8.0 where I added block contacts for valves and motl's. The sequence is like for example: -open valve 1 -close valve 2 -start pump -start heating -close valve 1 etc.. How do I define different start conditions? For example: The pump must go on, when there are no errors from valves 1 and 2, and where the feedback signals are as expected... The connection is made from sfc instance directly to the block so I cannot put a AND08 block in front of the pumps Auto_on command... I can do two things: Create the block contact connections and afterwards, put everywhere a AND block between SFC output and Block input (not a neat solution, also don't know if the connection still exists) or I have to make something like a HOLD sequence. If any errors are present, the hold sequence is triggered where I can use the TARGETSTEP and TARGETSEQ to set the SFC to a specific step after a specific error is reset... Another solution is to make a sequencer with alternative steps. Each step will check an error of a control module....If then the step is activated, different control modules will be stopped automatically.... and a restart is needed... How can I make this the best way possible.....? What are your solutions |
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| 1/22/2013 7:23 PM | |
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Joined: 3/14/2008 Last visit: 11/5/2024 Posts: 2122 Rating:
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Well, not exactly what I mean... Its sequential control in a continous process... When the SFC is completed and the function is activated: pumps running, valves opened etc.. How can I configure the fault sequence? Normally, I have a few conditions to the pump FwdAut command so a pump will startwhen those conditions are set,but with the block contacts, I don''t because its directly connected. Customer doesnt want the use of interlock blocks,What is the easiest way to make afault handling?You cant say: I put a big OR block to the HOLD parameter and whenone of thecontrol moduleshas a fault, the whole sequence is aborted/holded. Or is the use of block contacts in this case not a really good solution? |
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| 1/30/2013 12:20 PM | |
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Posts: 836 Rating:
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Sorry dude... I would have to figuere it out on he project itself. |
| 1/30/2013 1:04 PM | |
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Joined: 3/14/2008 Last visit: 11/5/2024 Posts: 2122 Rating:
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Yeah project specific...In general I think there is some difficulty between SFC and CFC namely the sequential control inegrated in continous control. In Batch, where SFC type is a must in my opinion...it is not a big issue... I was actually wondering about different solutions to bring the sequential and continous control more together.... But as for the project, I changed the whole logic... The SFC sends signal to the equipment to activate, where in a CFC, the handling of the specific equipment is handled. SFC will only activate and deactivate according to specific order... |
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