Details Of Parameters; Sampling Time (S3) - Mitsubishi Electric FX5 User Manual

Set item
■The following setting is required when using the limit cycle method (operation setting (ACT) (b6 of (s3)+1) is "1").
(s3)+25 PV value threshold
(hysteresis) width (SHPV)
(s3)+26 Output value upper limit (ULV)
(s3)+27 Output value lower limit (LLV)
(s3)+28 Wait setting from end of tuning
cycle to start of PID control
(KW)
■The following setting is required when using the timeout time after maximum ramp (operation setting (ACT) (b6 of (s3)+1) is "0" and (ACT) (b8 of (s3)+1) is
"1") with the step response method.
(s3)+25 Timeout time setting value
after maximum ramp (R)
detection
(s3)+26 These devices are occupied for internal processing of PID operation. Do not change data.
(s3)+27
*1 (s3)+20 to +24 become used only if b1, b2, or b5 are set to "1" to determine the action (ACT) (s3) of +1.
*2 For supported version of each setting, refer to Page 478 Added and Enhanced Functions.
10.6

Details of Parameters

This chapter describes the details of parameters.

Sampling time (s3)

Set the cycle time (ms) for the PID operation. Setting range: 1 to 32767 (ms)
• In PID control and auto-tuning (Limit cycle method)
Set the sampling time longer than the operation cycle of the PLC.
• In auto-tuning (Step response method)
Set the sampling time to 1000 ms (= 1 second) or more.
Maximum error
The maximum error of the sampling time (TS) is from "- (one operation cycle+1 ms)" to "+ (one operation cycle)."
• When the sampling time (TS) is a small value
Fluctuation of the maximum error described above may cause a problem. In such a case, execute the PID instruction in the
constant scan mode, or program it in a timer interrupt routine.
• When the sampling time (TS) is shorter than one operation cycle of the PLC
A PID operation error occurs, however when PID operation is executed, the sampling time (TS) is equal to the operation cycle
of the PLC. In such a case, use the PID instruction in a timer interrupt, and clear (s3)+7 just before executing the PID
instruction.
Description/Setting range
Set it according to measured value (PV)
fluctuation.
Set maximum value (ULV) of output value (MV).
Set minimum value (LLV) of output value (MV).
-50 to +32717 [%]
1 to 32767 [s]
Remarks
The setting below is required when the limit cycle method
is used (when the operation setting (ACT) b6 is set to
ON).
It is valid when operation setting (ACT) (b4 of (s3)+1) is
"1", (ACT) (b6 of (s3)+1) is "0" and (b8 of (s3)+1) is "1".
10 PID CONTROL FUNCTION
10.6 Details of Parameters
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