LSIS Master-K K200S - Page 205

Chapter 15 The PID function of K200S MASTER-K
15-20
2) SV (Set value)
SV (setting value : the designated value) and PV (process value : present value) of
K200S PID operation have the range 0 ~ 4000. The range is set with the consideration of
the resolution of A/D and D/A module of K200S series (12 bits) and offset value. When
setting the SV or PV, please be careful convert the analog value of control object
(temperature, velocity, etc.) to digital value that are the output of A/D convert module. For
example, assume that PID control is used for temperature control with Pt100 (operation
range : 0 °C ~ 250 °C), and the goal value is 100 °C. The equivalent digital output of A/D
module (voltage output range : 1 ~ 5V) is 1600 if the A/D module outputs 0 (1V) with 0 °C,
and 4000(5V) with 250 °C. Therefore, the input of SV should be 1600, not 100.
3) Ripple
The K3P-07BS and K3P-07CS CPU module perform auto -tuning operation based on the
frequency response method. PID parameters are obtained by On/Off operation during 1
cycle of PV variation. The RIPPLE parameter shows at which cycle the CPU module will
perform auto-tuning operation. If 0 is selected, the CPU will get PID parameters during
the first cycle of PV variation. If 1 is selected, the second cycle will be used. (refer figure
15.16 for detailed information) Other choice of RIPPLE parameter is not allowed. In
general case, select 1 for proper auto -tuning operation. The On/Off operation will be
occur at the 80% of PV value.
Fig. 15.16 An example of auto-tuning PID parameters
4) STAT
The PIDAUT instruction output a relevant error code when an error occurs during PID
operation. See the chapter 15.4.3 error code list for details
5) P / I / D
The calculated PID parameters are output to these words.
80% of PV
Perform A/T operation at the 1
st
cycle
(When the RIPPLE = 0)
Perform A/T operation at the 2
nd
cycle
(When the RIPPLE = 1)