LSIS XBE-DC08A, Руководство пользователя, Страница: 341 / 1284

B
asi
s
Chapter 6 Built-in PID Function
6-32
(c) SV
It sets the auto-tuning SV of a loop in question. Similar to PID control, physical values (temperature, flow rate, pressure and
etc) of an object to control is not meaningful and instead, it should use the physical amount of an object to control after
converting them into numerals. For instance, in order to control a system using a sensor that the output is 0V when its
heating device temperature is 0
℃
while it is 10V when the temperature is 100
℃
as much as 50
℃
, it is necessary to set
SV as 2000(as long as it uses AD input module XBE-AD04A).
(d) Operation time
It sets the cycle to execute operation for auto-tuning. The setting cycle is 0.1ms and available between 10ms ~ 6553.5ms
(setting value: 100 ~ 65,535) while it is set at a unit of integer per 0.1ms.
(e) Max./min. MV
It sets the max./min. value of output for auto-tuning. The available scope is between -32,768 ~ 32,767. If the max. MV is set
lower than min. MV, the auto-tuning function of a loop generates an error and does not work.
(f) Hysteresis setting
Looking at relay tuning in Figure 6.15, it shows it outputs the max. MV as auto-tuning starts but it converts to min. output as
PV is over SV and then, it converts to the max. output as PV is lower than SV. However, if input PV contains noise
components or reply components, auto-tuning ends by a slight vibration of PV around SV, yielding incorrect tuning result.
To prevent it, hysteresis may be set. XGB auto-tuning converts output at SV + Hysteresis when PV increases or at SV –
Hysteresis when it decreases once hysteresis is set. With it, it may prevent incorrect tuning by a slight vibration around SV.
[Figure 6.16 Example of Hysteresis setting ]
PV
MV
SV
Hysteresis
SV+Hysteresis
SV- Hysteresis