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4-172 Series 90-30/20/Micro Programmable Controllers Reference Manual – September 1998 GFK-0467K
4
Parameters:
Parameter Description
enable When enabled through a contact, the PID function is performed.
SP SP is the control loop or process set point. Set using PV Counts, the PID adjusts the
output CV so that PV matches SP (zero error).
PV Process Variable input from the process being controlled, often a %AI input.
MAN When energized to 1 (through a contact), the PID block is in MANUAL mode. If the
PID block is on manual off, the PID block is in automatic mode.
UP If energized along with MAN, it adjusts the CV up by 1 CV per solution.*
DN If energized along with MAN, it adjusts the CV down by 1 CV per solution.*
RefArray
Address
Address is the location of the PID control block information (user and internal
parameters). Uses 40 %R words that cannot be shared.
ok The ok output is energized when the function is performed without error. It is off if
error(s) exist.
CV CV is the control variable output to the process, often a %AQ analog output.
*Incremented (UP parameter) or decremented (DN parameter) by one (1) per access of the PID function.
Valid Memory Types:
Parameter flow %I %Q %M %T %S %G %R %AI %AQ const none
enable •
SP • • • • • • • • •
PV • • • • • • • •
MAN •
UP •
DN •
address •
ok • •
CV • • • • • • • •
• Valid reference or place where power may flow through the function.