Program Example For Changing The Pid Control Mode Between Automatic And Manual - Mitsubishi Electric MELSEC-Q series Programming Manual

Program example for changing the PID control mode between
automatic and manual
An example program for switching between automatic and manual modes while executing PID operation is described below.
[PROGRAMMINGCONDITIONS]
• PID operation is executed for 1 loop.
• The sampling cycle is 1 second.
• The PID control data is set in the following devices:
PID control data
Common data
Loop 1 data
• The I/O data is set in the following devices:
I/O data
Common data
Loop 1 data
• The SV and MV in manual mode are set with external digital switches as follows:
Item
SV
MV (manual control mode)
• The following devices are used to start and stop PID control and the automatic/manual changeover command:
Command
PID control start command
PID control stop command
SV setting command
MV setting command in manual mode
Automatic/manual mode changeover command
• The digital values of the Q64AD and Q62DA are set within the range 0 to 2000.
• The PID bumpless processing flag, SM794, is set to OFF. In the manual mode, the SV is automatically rewritten to the PV
when PID operation is performed. Therefore, when the manual mode is returned to the automatic mode, the SV must be
rewritten to the one used in the automatic mode before switching to the manual mode. The SV is rewritten step-by-step 10
times as illustrated below:
*1 The SV is rewritten using the operation method illustrated below:
The incremental value obtained with the formula above is added to SV every second. The remainder is added in the first addition
operation.
*1
8 INCOMPLETE DERIVATIVE PID CONTROL INSTRUCTIONS AND PROGRAM EXAMPLES
Device name
D500 to D501
D502 to D515
Device name
D600 to D609
D610 to D632
Device name
X30 to X3F
X20 to X2F
Device name
X0
X1
X3
X4
X6 (OFF: Automatic mode, ON: Manual mode)
8.2 PID Control Program Examples
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