Temperature Ramp

phil hughes · Dec 30, 2013

We are using a AB Compact Logix L24 ER PLC. Version 20 Logix Software.The process is heating and cooling a tank jacket. We would like to limit the P.V in our P.I.D at a rate of 5 deg / min.
I have looked through previous posts and can’t find anything similar. The RMPS Function block looks overkill and the RLIM I am unsure about. Any input would be appreciated.
Thanks
Phil

NetNathan · Dec 30, 2013

Just build a ramp block....
You probably do not want to ramp at adding 5 degrees every minute.

So lets break it down...to seconds.
60/5=1 degree every 12 seconds or 0.5 degrees every 6 seconds or 0.25 degrees every 3 seconds.

For 0.5 degree ramp...
Use a timer and counter to build the ramprate and just add 0.5 degrees to the ramprate every 6 seconds. (The ramp rate is the SP in your PID block.)
Then use a compare function to stop the ramp...When ramprate = soak temperature then stop ramp.

Temperature Ramp

phil hughes

Lifetime Supporting Member

NetNathan

Lifetime Supporting Member

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