dcooper33
Lifetime Supporting Member + Moderator
Hi guys,
I'm hoping someone here has dug into this before. I've been tasked with trying to "figure out" why a barrel heating/cooling system has never worked very well. It takes too long to heat up, overshoots the setpoint, and the temperature feedback is erratic.
Here's the set-up:
1756-L61 processor v15.3 talking to 4 remote flex i/o racks over RIO (1794-ASB, 2 racks for digital i/o, and two for the thermo cards).
We're using PIDE FB's feeding SRTP's to pulse the heating and cooling of each zone.
I'm pretty new to RS5k, and to FB's, but I've already found quite a bit wrong with the programming, such as the Block Transfers to move the thermocouple data to the PIDE's is set-up on a 5 second loop(!) while the the PIDE's are called in a periodic task every second.
A bigger issue, I think, is the large amount of dead-time inherent in the system, which is causing the integrator to wind-up before the PV even changes. There's lots of things I could do to try to correct this, like setpoint ramping, and gain scheduling, but before I do that, I want to be able to monitor the integral sum so I can see when would be a good time to enable and disable integration.
I haven't been able to find the I sum in the controller tags or in the PIDE configuration. I also haven't been able to find anything in the literature or online help that points to it.
If anybody has any info on where to find the I sum, or any advice on dealing with the PIDE in these kind of applications, I'd appreciate hearing it. This is also my first time working with a velocity-type PID equation.
Thanks in advance,
Dustin
I'm hoping someone here has dug into this before. I've been tasked with trying to "figure out" why a barrel heating/cooling system has never worked very well. It takes too long to heat up, overshoots the setpoint, and the temperature feedback is erratic.
Here's the set-up:
1756-L61 processor v15.3 talking to 4 remote flex i/o racks over RIO (1794-ASB, 2 racks for digital i/o, and two for the thermo cards).
We're using PIDE FB's feeding SRTP's to pulse the heating and cooling of each zone.
I'm pretty new to RS5k, and to FB's, but I've already found quite a bit wrong with the programming, such as the Block Transfers to move the thermocouple data to the PIDE's is set-up on a 5 second loop(!) while the the PIDE's are called in a periodic task every second.
A bigger issue, I think, is the large amount of dead-time inherent in the system, which is causing the integrator to wind-up before the PV even changes. There's lots of things I could do to try to correct this, like setpoint ramping, and gain scheduling, but before I do that, I want to be able to monitor the integral sum so I can see when would be a good time to enable and disable integration.
I haven't been able to find the I sum in the controller tags or in the PIDE configuration. I also haven't been able to find anything in the literature or online help that points to it.
If anybody has any info on where to find the I sum, or any advice on dealing with the PIDE in these kind of applications, I'd appreciate hearing it. This is also my first time working with a velocity-type PID equation.
Thanks in advance,
Dustin