GE 90-30/20/Micro manual Internal Parameters in RefArray

4

Table 4-5. PID Parameters Details - Continued

Data Item				Description
Manual	This is an INT value set to the current CV output while the PID block is in Automatic
Command	mode. When the block is switched to Manual mode, this value is used to set the CV
(13)	output and the internal value of the integrator within the Upper and Lower Clamp and
	Slew Time limits.
Control Word	This is an internal parameter that is normally left at 0.
(14)	If the Override low bit is set to 1, this word and other internal SP, PV and CV
	parameters must be used for remote operation of this PID block (see below). This
	allows remote operator interface devices, such as a computer, to take control away
	from the PLC program. Caution: if you do not want this to happen, make use the
	Control Word is set to 0. If the low bit is 0, the next 4 bits can be read to track the
	status of the PID input contacts as long as the PID Enable contact has power. A
	discrete data structure with the first five bit positions in the following format:
	Bit: Word Value: Function: Status or External Action if Override bit set to 1:
	0	1	Override	If 0, monitor block contacts below. If 1, set
				them externally.
	1	2	Manual/	If 1, block is in Manual mode; other numbers
			Auto	it is in Automatic mode.
	2	4	Enable	Should normally be 1; otherwise block is
				never called.
	3	8	UP/Raise	If 1 and Manual (Bit 1) is 1, CV is being
				incremented every solution.
	4	16	DN/LowerIf 1 and Manual (Bit 1) is 1, CV is
				being incremented every solution.
SP (15)	(Non-configurable–set and maintained by the PLC)				Tracks SP in; must be set
	externally if Override = 1.
CV (16)	(Non-configurable–set and maintained by the PLC)				Tracks CV out.
PV (17)	(Non-configurable–set and maintained by the PLC)				Tracks PV in; must be set
	externally if Override bit = 1.
Output (18)	(Non-configurable–set and maintained by the PLC)				This is a signed word
	value representing the output of the function block before the application of
	the optional inversion. If no output inversion is configured and the output
	polarity bit in the control word is set to 0, this value will equal the CV output. If
	inversion is selected and the output polarity bit is set to 1, this value will equal the
	negative of the CV output.
Diff Term	Used internally for storage of intermediate values. Do not write to this location.
Storage (19)
Int Term	Used internally for storage of intermediate values. Do not write to this location.
Storage (20/21)
Slew Term	Used internally for storage of intermediate values. Do not write to this location.
Storage (22)
Clock (23–25)	Internal elapsed time storage (time last PID executed). Do not write to these locations.
Y Remainder (26)	Holds remainder for integrator division scaling for 0 steady state error.
Lower and	Optional INT values in PV Counts that define the highest and lowest display value for
Upper Range	the SP and PV Logicmaster Zoom key horizontal bar graph and ADS PID faceplate
(27/28)	display.
Reserved (29–34	29–34 are reserved for internal use; 35–39 are reserved for external use. They are
and 35–39)	reserved for GE Fanuc use, and cannot be used for other purposes.

Internal Parameters in RefArray

4-178 Series 90-30/20/Micro Programmable Controllers Reference Manual–September 1998 GFK-0467K