Chapter 7 Usage of Various Functions

Proportional gain

The MASTER-K120S can handle only integer, not the floating point type. Therefore, to enhance the accuracy of PID operation, the PID8 instruction is designed to input the P_GAIN data as the 100 times scaled up. For example, if the designated P_GAIN is 98, actual input data of P_GAIN should be 9800. If the designated P_GAIN is 10.99, input 1099 to the P_GAIN.

Derivative time and integral time

I_TIME and D_TIME are 10 times scaled up. For example, input 18894 if the designated I_TIME value is 1889.4. The range of actual input is 0 ~ 20000. (it is possible that parameter value designates ‘D’ area also)

Mode command set

In MASTER-K120S, only the following 7 operation modes are available. Other operation modes, such as PD or I, are not permitted.

No.

 

EN_P

 

EN_I

 

EN_D

 

PWM output

 

Operation

1

1

(enable)

0

(disable)

0

(disable)

 

 

 

P operation

2

1

(enable)

1

(enable)

0

(disable)

 

0 (disable)

 

PI operation

3

1

(enable)

1

(enable)

1

(enable)

 

 

 

PID operation

4

1

(enable)

0

(disable)

0

(disable)

 

 

 

P operation/PWM output

5

1

(enable)

1

(enable)

0

(disable)

 

1 (enable)

 

PI operation/PWM output

6

1

(enable)

1

(enable)

1

(enable)

 

 

 

PID operation/PWM output

7

0

(disable)

0

(disable)

0 (disable)

 

0 (disable)

 

On/Off operation

PWM set

PWM(Pulse Width Modulation) is a output method which changes on-off duty of output pulses by calculated manipulation value. Fig 7.9 shows example of PWM output. Using PWM output, PID control system can be constructed easily without D/A conversion module and power regulator.

When PWM is designates , ‘scan time’ item is disabled and ‘PWM’ items can be designated. In this case, scan time is set to designated PWM output period. The range of PWM output period is 1 ~ 10 seconds, and actual input range is 10 ~ 100. PWM output point is only available for output contact of main unit.

Example) PWM output period : 1s, Output contact : P40, MV limit range : 0~4000

 

MV = 2000

MV = 1000

0.5s

0.5s

0.25s

0.75s

On

 

 

 

P40

 

 

 

 

 

 

Time

7-27

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