GE 90-30/20/Micro manual PID Parameters Overview

4

Table 4-4. PID Parameters Overview (Continued)

Register	Parameter	Low Bit Units	Range of Values
%Ref+0019	Diff Term Storage	N/A; set and	Non-configurable
		maintained by the
		PLC
%Ref+0020	Int Term Storage	N/A; set and	Non-configurable
and		maintained by the
%Ref+0021		PLC
%Ref+0022	Slew Term Storage	N/A; set and	Non-configurable
		maintained by the
		PLC
%Ref+0023	Clock	N/A; set and
%Ref+0024		maintained by	Non-configurable
%Ref+0025	(time last executed)	the PLC
%Ref+0026	Y Remainder Storage	N/A; set and
		maintained by the	Non-configurable
		PLC
%Ref+0027	Lower Range for SP, PV	PV Counts	–32000 to 32000 (>%Ref+28) for
			display
%Ref+0028	Upper Range for SP, PV	PV Counts	–32000 to 32000 (<%Ref+27) for
			display
%Ref+0029
•	Reserved for internal use	N/A	Non-configurable
%Ref+0034
%Ref+0035
•	Reserved for external use	N/A	Non-configurable
%Ref+0039

The RefArray array must be %R registers on the 90-30 PLC. Note that every PID block call must use a different 40-word array even if all 13 user parameters are the same because other words in the array are used for internal PID data storage. Make sure the array does not extend beyond the end of memory.

To configure the user parameters, select the PID function and press F10 to zoom in to a screen displaying User Parameters; then use arrow keys to select fields and type in desired values. You can use 0 for most default values, except the CV Upper Clamp, which must be greater than the CV Lower Clamp for the PID block to operate. Note that the PID block does not pass power if there is an error in User Parameters, so monitor with a temporary coil while modifying data.

Once suitable PID values have been chosen, they should be defined as constants in the BLKMOV so that they can be used to reload default PID user parameters if needed.

4-174 Series 90-30/20/Micro Programmable Controllers Reference Manual–September 1998 GFK-0467K