When the PID instruction is enabled, the PID is calculated and
the operation volume is adjusted and output (calculated). When the
instruction is disabled as below, it outputs the Tieback value. The
Tieback value is specified in S3. Input the constant 0 if no output
is necessary when the instruction is disabled.
To use the PID instruction in a logic program, allocate
variables to the PID variable operand (HP) and the integer variable
operands (S1, S2, S3 and D1) first.
PID Variable
When you allocate a variable to the PID instruction operand HP,
a member is automatically allocated to the variable.
PID Variable
Variables Settings
Description
VariableName.Q
Bit Variable
Completion Flag for PID Instruction
Processing
VariableName.PF
Bit Variable
Processing Deadband Range Flag
VariableName.UO
Bit Variable
Output Values over the Lower Limit
VariableName. to
Bit Variable
Output Values over the Upper Limit
VariableName.IF
Bit Variable
Integral Setting
VariableName.KP
Integer Variable
Proportional Constant
VariableName.TR
Integer Variable
Integral Calculus Time
VariableName.TD
Integer Variable
Differential Calculus Time
VariableName.PA
Integer Variable
Processing Deadband Range
VariableName.BA
Integer Variable
Bias (Offset)
VariableName.ST
Integer Variable
Frequency in Sampling
Values assigned to a proportional constant,
integral calculus time, and differential calculus time look
different when input in "PID Monitor" from when input to each of
the PID variables in a program. When inputting the values in the
program, multiply the values by 1000 for the proportional constant,
the integral calculus times and the differential calculus
times.
For example, proportional constant 0.1 x 1000 -> 100
All the PID variables are keep-type
variables. Up to 8 PID instructions are allowed per project.
1 PID instruction can be specified for 1 PID
variable.