LG Electronics 120S user manual Introduction, Manipulation Value

Chapter 7 Usage of Various Functions

7.1.5 PID control function(Standard type only)

1) Introduction

This chapter will provide information about the built-in PID (Proportional Integral Derivative) function of MASTER-K120S main unit. The MASTER-K120S series does not have separated PID module like MASTER-K300S and MASTER- K1000S series, and the PID function is integrated into the main unit.

The PID control means a control action in order to keep the object at a set value (SV). It compares the SV with a sensor measured value (PV : Present Value) and when a difference between them (E : the deviation) is detected, the controller output the manipulate value (MV) to the actuator to eliminate the difference. The PID control consists of three control actions that are proportional (P), integral (I), and derivative (D).

Set Value

Present Value

SV

PV

P I D calculation

Manual MV

MV	Manipulation		D/A
	value
			converting
		Automated MV
			module

Control

object

A/D converting	Sensor
module

The characteristics of the PID function of MASTER-K120S is as following;

•the PID function is integrated into the CPU module. Therefore, all PID control action can be performed with instruction (PID8,PID8AT) without any separated PID control module.

•P operation, PI operation, PID operation and On/Off operation can be selected easily.

•PWM(Pulse Width Modulation) output is available.

•The manual output (the user-defined forced output) is available.

•By proper parameter setting, it can keep stable operation regardless of external disturbance.

•The operation scan time (the interval that PID controller gets a sampling data from actuator) is changeable for optimizing to the system characteristics.

•SV Ramp and Delta MV function are available.

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