IDEC OpenNet series

20: PID INSTRUCTION
20-12 OPENNET CONTROLLER USER’S MANUAL
Source Operand S3 (Set Point)
The PID action is executed to adjust the process variable (S1+0) to the set point (S3).
When the linear conversion is disabled (S1+4 set to 0), set a required set point value of 0 through 4000 to the operand des-
ignated by S3. Valid operands are data register and constant.
When the linear conversion is enabled (S1+4 set to 1), designate a data register as operand S3 and set a required set point
value of –32768 through 32767 to the data register designated by S3. Since the PID instruction uses the word data type,
negative constants cannot be entered directly to operand S3. Use the MOV instruction with the integer (I) data type to store
a negative value to a data register. The set point value (S3) must be larger than or equal to the linear conversion minimum
value (S1+6) and smaller than or equal to the linear conversion maximum value (S1+5).
When an invalid value is designated as a set point, the PID action is stopped and an error code is stored to the data register
designated by S1+2. See Operating Status on page 20-3.
Source Operand S4 (Process Variable before Conversion)
The analog output from the transducer is inputted to the analog input module, which converts the input data to a digital
value of 0 through 4000. The digital value is stored to a link register L100 through L705 depending on the mounting posi-
tion of the analog input module and the analog input channel connected to the transducer. Designate a link register as
source operand S4 to store the process variable.
For example, when the analog input module is mounted in the first slot from the CPU module among all functional mod-
ules such as analog I/O and OpenNet interface modules (not including digital I/O modules) and when the analog input is
connected to channel 0 of the analog input module, designate link register L100 as source operand S4. When the analog
input module is mounted in the third slot and the analog input is connected to channel 4, designate link register L304 as
source operand S4.
Link Register Allocation Numbers for Source Operand S4
When an analog input module is not used, a data register can also be designated by source operand S4 (process variable).
When designating a data register as S4, make sure that the S4 data takes a value between 0 and 4000. When S4 stores a
value larger than 4000, the process variable is set to 4000.
Analog Input Module Position
Analog Input Channel
012345
Functional Module 1 L100 L101 L102 L103 L104 L105
Functional Module 2 L200 L201 L202 L203 L204 L205
Functional Module 3 L300 L301 L302 L303 L304 L305
Functional Module 4 L400 L401 L402 L403 L404 L405
Functional Module 5 L500 L501 L502 L503 L504 L505
Functional Module 6 L600 L601 L602 L603 L604 L605
Functional Module 7 L700 L701 L702 L703 L704 L705
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