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10 PID CONTROL INSTRUCTIONS
10.3 PID Control Instructions (Exact Differential)
• Write data to the I/O data "Write" area by users with the program. Users can read data from the I/O data "Read" area with
the program. Never attempt to write data to the area indicated by "Read/write disabled" or "Read"; otherwise, normal
operation can no longer be performed. Note that, when starting control from the initial status, the data areas must be
cleared by the program.
• Even when the manual manipulated value (MV
MAN
) is output in manual mode, execute the PIDCONT(P) instruction every
scan. Unless the PIDCONT(P) instruction is executed, the bumpless function cannot be performed.
• Apply an interlock using the READY signal of each module so that the PIDCONT(P) instruction is executed only when the
A/D converter module used to obtain the process value (PV) and the D/A converter module used to output the manipulated
value (MV) are normal. If the instruction is executed when these modules are not normal, PID operation cannot be
performed normally as the result of failure in normal acquisition of process values (PV) or in normal output of manipulated
values (MV).
(1) Control command
(2) READY signal of the A/D converter module
(3) READY signal of the D/A converter module
Error code
(SD0)
Description
3405H The value of the data set in the I/O data area specified by (s) is out of the setting range.
3422H The PIDINIT(P) instruction is not executed before the PIDCONT(P) instruction.
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