XGB Analog edition manual
15 - 36
(b) PWM output enable
PWM output means an output method to turn a junction on – off with a duty proportional to control
output calculated by a uniform output cycle. If PWM output is enabled, it realizes PWM output in
accordance with PWM output cycle set in the parameter of PWM output junction (P20 ~ P3F, in
case of IEC type, %QX0.0.0~%QX0.0.15) designated in the parameter. At the moment, the PWM
output cycle follows the PWM output cycle separately set in auto-tuning operation cycle.
(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 15.15, 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 15.16 Example of Hysterisis setting ]
To Next Page
Loading...