Valve Sequence

dskplc · Mar 27, 2017

Hello, I am puzzled why my valve sequence doesn't continually repeat since I have a Valve6 timer not done to make it continually run. Please see pictures of my code. I also wrote a simulation routine but thought this was good. I really appreciate your advice. Thank you.

sparkie · Mar 27, 2017

The pictures were pretty blurry, but from the looks of it you need to break the rung that energizes your valve 6 timer. The valve 6 timer is staying energized and preventing the process from restarting. Try putting an XIO for the Valve6.DN bit on the rung with the valve 6 timer.

Then it should keep the rung energized while the timer is not done and deenergize the rung when the timer completes allowing your process to restart.

Another option would be to add this rung:

] valve6.DN [----------------------------------(RES) for the valve6 timer

dskplc · Mar 27, 2017

Better screenshot

Hello Sparkie, Sorry about the blurry pic! I have attached a better one. Thanks. In the meantime I will try what you suggested.

dskplc · Mar 27, 2017

Almost there?

Hi Sparkie, Thanks to you I got the sequence to continually go but wondering why the timer for valve 6 doesn't complete my required time of 70 sec but resets at around 10 sec. Please see next screenshot attached. Thank you very much for your help!

mike_dr · Mar 27, 2017

maybe valve4openfeedback is true

sparkie · Mar 27, 2017

On rung3 you need to be using Valve6.DN as your XIO

mike_dr · Mar 27, 2017

is this the sequence? http://prntscr.com/eoy975 if yes, then try doing it in a state machine logic, it's more efficient. if you just base it on open feedback it would cause trouble.

dskplc · Mar 27, 2017

Thank you for this. My supervisor said this but I didn't quite understand how to write the PLC code for this but will try to understand. Thanks!

dskplc · Mar 27, 2017

mike dr. Thanks again for the sequence. I was wondering if these open and close are all digital inputs or outputs or both. Right now I have DIs as ValvexOpenFeedback and Dos as ValveOpenCmd. I really appreciate your help.

mike_dr · Mar 27, 2017

open and close in the box are Cmd while the conditions are beside the arrow,where you put the OpenFB with timer. for the conditions, do XIC StartPB OTE Trgger.1 then do the state logic.For output, you use XIC state.1 OTE valveXOpenCmd.

dskplc · Mar 27, 2017

mick dr. I got a bit lost in your explanation but have attached my acd file to see if this is what you mean? It is in the routine "scratch". If I use my first idea non-state logic for the valve sequence the timers don't finish the schedule timing and drops out too soon. Not sure why but someone said it might be an input?

mike_dr · Mar 28, 2017

you have not answered my question if thats the sequence but as I said, you cant just make the openfeedback your condition of opening/closing the next valve as openFB will turn off once the other valve turns on, which happens on valve6. better to use a MOV state_dint and make that signify what state the program is in and use it as a condition in opening the valve. I cant open your file, don't have that version of RS

Valve Sequence

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