IAP Technique-Faceplate for a CL/HPM sequence

If you want to know how to produce a HPM control sequence with a real faceplate this is the page for you.

Summary

CL/HPM sequences are very useful however Honeywell have not included a very user-friendly way of interfacing with the sequence when your application is a type of regulatory control.

This technique shows you how to build a faceplate for a CL/HPM sequence so that you get a similar interface to that for a CL/AM program. Best of all you can use the initialisation and limiting functions built into a PID control algorithm and save yourself some programming.

Why use this technique

The most frequent application of this technique is for custom CL/HPM regulatory type control schemes.

Typical applications are:

xxx

Implementation

Build yourself an HPM regulatory controller but with the following specific configuration

Note the use of *.OPEU . That is what is actually entered as the configuration item. It means "my OPEU signal". Also the OPEUHI and OPEULO values have to be provided. Normally this are automatically set (except for PID-ERFB algorithm) by making them equal to the input range of the entity to which the controller is connected. Since there is no output connection in this case they need to be entered manually.

The value of T1 should be chosen according to how fast you want the output to attain the user entered value. Note that this loop cannot become unstable so even the maximum integral action (T1 = 0.03) will not cause problems. Typically values of 0.05 through 0.2 are suitable for most situations.

To use this in a scheme just pull in the .OPEU parameter from this controller into your scheme.

Alternatives

It is possible to use a numeric, an auto manual regulatory controller or a regulatory PV but there are several advantages that an integral only controller has over all of these.

	I only Reg C	Numeric	Auto Man Reg C	Reg PV
Set in engineering units
Range limiting
Ability to ramp
Initialisation
Small resource usage

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