IDEC MicroSmart - Manual (Page 360)

21: PID I NSTRUCTION
21-4 « FC4A M ICRO S MART U SER ’ S M ANUAL »
S1+0 Process Variable (after conversion)
When the linear conversion is enabled (S1+4 set to 1), the data register designated by S1+0 stores the linear conversion
result of the process variable (S4). The process variable (S1+0) takes a value between the linear conversion minimum
value (S1+6) and the linear conversion maximum value (S1+5).
When the linear conversion is disabled (S1+4 is set to 0), the data register designated by S1+0 stores the same value as the
process variable (S4).
S1+1 Output Manipulated Variable
While the PID action is in progress, the data register designated by S1+1 holds 0 through 100 read from the manipulated
variable, –32768 through 32767, stored in the data register designated by D1, omitting values less than 0 and greater than
100. The percent value in S1+1 determines the ON duration of the control output (S2+6) in proportion to the control
period (S1+13).
While manual mode is enabled with the auto/manual mode control relay (S2+1) set to on, S1+1 stores 0 through 100 read
from the manual mode output manipulated variable (S1+18).
While auto tuning (AT) is in progress, S1+1 stores 0 through 100 read from the AT output manipulated variable (S1+22).
S1+2 Operating Status
The data register designated by S1+2 stores the operating or error status of the PID instruction.
Status codes 1X through 6X contain the time elapsed after starting auto tuning or PID action. X changes from 0 through 9
in 10-minute increments to represent 0 through 90 minutes. The time code remains 9 after 90 minutes has elapsed. When
the operation mode (S1+3) is set to 1 (AT+PID), the time code is reset to 0 at the transition from AT to PID.
Status codes 100 and above indicate an error, stopping the auto tuning or PID action. When these errors occur, a user pro-
gram execution error will result, turning on the ERR LED and special internal relay M8004 (user program execution
error). To continue operation, enter correct parameters and turn on the start input for the PID instruction.
Status Code Description Operation
1X AT in progress
AT is normal.
2X AT completed
5X PID action in progress
PID action is normal.
6X
PID set point (S3) is reached. Status code changes from 5X to 6X once the PID set point is
reached.
100 The operation mode (S1+3) is set to a value over 2.
PID action or AT is
stopped because of
incorrect parameter
settings.
101 The linear conversion (S1+4) is set to a value over 1.
102
When the linear conversion is enabled (S1+4 to 1), the linear conversion maximum value
(S1+5) and the linear conversion minimum value (S1+6) are set to the same value.
103
The output manipulated variable upper limit (S1+16) is set to a value smaller than the out-
put manipulated variable lower limit (S1+17).
104
When the linear conversion is enabled (S1+4 set to 1), the AT set point (S1+21) is set to a
value larger than the linear conversion maximum value (S1+5) or smaller than the linear con-
version minimum value (S1+6).
105
When the linear conversion is disabled (S1+4 set to 0), the AT set point (S1+21) is set to a
value larger than 4095.
106
When the linear conversion is enabled (S1+4 set to 1), the set point (S3) is set to a value
larger than the linear conversion maximum value (S1+5) or smaller than the linear conver-
sion minimum value (S1+6).
107
When the linear conversion is disabled (S1+4 set to 0), the set point (S3) is set to a value
larger than 4095.
200
The current control action (S2+0) differs from that determined at the star t of AT. To restar t
AT, set correct parameters referring to the probable causes listed below:
• The manipulated variable (D1) or the control output (S2+6) is not outputted to the control
target correctly.
• The process variable is not stored to the operand designated by S4.
• The AT output manipulated variable (S1+22) is not set to a large value so that the process
variable (S4) can change sufficiently.
• A large disturbance occurred.
AT is stopped because
of AT execution error.
201
AT failed to complete normally because the process variable (S4) fluctuated excessively. To
restar t AT, set the AT sampling period (S1+19) or the input filter coefficient (S1+11) to a
larger value.