PIDE conversions

I am building a new control console for our extremely outdated Heat Treat Oven and was wondering if someone could assist me with an issue I'm having.

The Heaters are currently being controlled with a Yokogawa UP550 controller and I am replacing recipe control and temperature control with a PLC.

My issue is, I can't seem to figure out what the P,I,D variables in the existing controller would convert to in the Compact Logix AB PIDE setpoints.

I am attempting to do this to minimize downtime and tuning issues on installation.

Current Controller
1.P = 1.3%
1.I = 51 Secs
1.D = 13 Secs

In the PIDE control what would those settings represent?

Any Assistance would be greatly appreciated
Thank you
Duane

Here's a guess and I'll provide some rationale but don't get your hopes too high. I briefly looked at Yokogawa's documentation and couldn't find the form of the controller used.

Use Rockwell's dependent form on the PIDE template. This uses rate and reset in terms of minutes, so divide the yokogawa rate and reset terms by 60 to get the corresponding PIDE terms. Next, Yokogawa would seem to use proportional band. Nominally, 100/PB = Gain, so make your PIDE gain equal to 100/1.3 (seems high but may not be if you're using a thermocouple with a large temperature range).

One thing you'll want to note are the instrument input and output ranges configured in the Yokogawa because any changes made to these ranges can affect the effective proportional gain of the controller.

Good luck.

Thanks James,

We are using a K-type thermocouple with a range from -330 °F to +2498 °F range so I would say that is a pretty broad range. I was thinking the same thing but for some reason a 76.923 SP on the KI sounded really high to me.

I appreciate your response, at least it told me I was thinking on the right terms.

one other thing...

I have more confidence about the integral and derivative term suggestions than the proportional gain. So, if at first my suggestions seem obviously way off based on the process behavior, I'd try adjusting the proportional gain before you completely jettison my recommendation. Good luck.

Dauge said:

I am building a new control console for our extremely outdated Heat Treat Oven and was wondering if someone could assist me with an issue I'm having.

The Heaters are currently being controlled with a Yokogawa UP550 controller and I am replacing recipe control and temperature control with a PLC.

My issue is, I can't seem to figure out what the P,I,D variables in the existing controller would convert to in the Compact Logix AB PIDE setpoints.

I am attempting to do this to minimize downtime and tuning issues on installation.

Current Controller
1.P = 1.3%
1.I = 51 Secs
1.D = 13 Secs

In the PIDE control what would those settings represent?

Click to expand...

The first question is what does the 1.P gain mean? It is probably percent output per degree or count of error.

The I and D gains should only need to be divided by 60 to convert seconds to minutes.

The ISA PID controller usually has one gain in percent control output per unit of error. The I and I parameters are usually time constants in minutes.