PID instruction timing diagrams

The following timing diagram examples describe execution scenarios for the PID instruction.

Successful PID execution

Successful PID execution
Successful PID execution
Scan cycle description
Scan Cycle
Description
1, 8
Rung condition becomes TRUE when:
  • Enable input bit is TRUE.
  • Input parameters are valid.
  • Active bit is TRUE.
  • Error bit is FALSE.
2,3,4
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are valid.
  • Updates PID output parameters.
5, 9
Rung condition becomes FALSE when:
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.
6, 7, 10, 11
No change in Rung condition.
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.

PID execution with Error

PID execution with Error
PID execution with Error
Scan cycle description
Scan Cycle
Description
1, 8
Rung condition becomes TRUE when:
  • Enable input bit is TRUE.
  • Input parameters are invalid.
  • Active bit is FALSE.
  • Error bit is TRUE. ErrorID output is set.
  • CV output is set to 0.
  • AbsoluteError calculates based on PV and SP input values.
2,3,4
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are not valid.
  • Updates PID output parameters.
5, 9
Rung condition becomes FALSE when:
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.
6, 7, 10, 11
No change in Rung condition.
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.

PID execution with Error then successful execution

PID execution with Error then successful execution
PID execution with Error then successful execution
Scan cycle description
Scan Cycle
Description
1, 8
Rung condition becomes TRUE when:
  • Enable input bit is TRUE.
  • Input parameters are not valid.
  • Active bit is FALSE.
  • Error bit is TRUE. ErrorID output is set.
  • CV output is set to 0.
  • AbsoluteError calculates based on PV and SP input values.
2
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are not valid.
  • Updates PID output parameters.
3, 4
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are valid.
  • Active bit is TRUE.
  • Error bit is FALSE.
  • Updates PID output parameters.
5, 9
Rung condition becomes FALSE when:
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.
6, 7, 10, 11
No change in Rung condition.
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.

Successful PID execution and Error

Successful PID execution and Error
Successful PID execution and Error
Scan cycle description
Scan Cycle
Description
1, 8
Rung condition becomes TRUE when:
  • Enable input bit is TRUE.
  • Input parameters are valid.
  • Active bit is TRUE.
  • Error bit is FALSE.
  • Update PID output parameters.
2
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are valid.
  • Update PID output parameters.
3, 4
No change in Rung condition.
  • Enable input bit is TRUE.
  • Input parameters are invalid.
  • Error bit is TRUE. ErrorID output is set.
  • CV output is set to 0.
  • AbsoluteError calculates based on PV and SP input values.
5, 9
Rung condition becomes FALSE when:
  • Enable bit is FALSE.
  • Clear PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.
6, 7, 10, 11
No change in Rung condition.
  • Enable bit is FALSE.
  • Clears PID output parameters except AbsoluteError.
  • AbsoluteError calculates based on PV and SP input values.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.
Normal