LG Electronics 120S user manual Usage of Various Functions

Chapter 7 Usage of Various Functions

⑩SV Ramp

If a large amount of SV changes during PID operation, The deviation(E) changes rapidly. Then manipulation value(MV) is changed rapidly also. This can cause damage on load or actuator. To prevent this situation, SV can be changed step by step by parameter setting.

Setting range is 1~4000(Default value is 1). Setting value represents the number of time which taken from starting set value to last set value.

For example, if SV-ramp is set to 1000 and SV changed from 1000 to 3000 during operation, it changes 2 every scan and reach 3000 after 1000 scan time.

Changed SV

Current SV

SV Ramp = 1

SV Ramp is designates

SV Ramp * Scan time

Time

⑪Delta MV

This is useful when wants to limit maximum change of manipulation value.

Setting range is 0 ~ 4000 and default value is 4000.

⑫Bias

The Bias data is used for the compensation of offset in the proportional control. The range of input is 0 ~ 4000. Be cautious that The actual range of Bias is –2000 ~ 2000. namely, 0~2000 represents 0 ~ +2000 and 2001 ~ 4000 represents -1 ~ -2000.

Example> If offset(SV-PV) is 100 → Bias should be 100. If offset(SV-PV) is -100 → Bias should be 2100.

⑬SV(Target) and PV(Current)

SV (setting value : the designated value) and PV (process value : present value) of MK120S 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 MK120S series (12bits) and offset value.

⑭PID Algorithm

In MASTER-K120S, two type of PID algorithm is available, The velocity form(Speed) and positioning form. Velocity form(Speed) operates incremental manners. Namely, It calculates the change(∆ n) required from previous manipulate value(MVn-1), But positioning form calculates an absolute manipulate value(MVn) every sampling steps. Generally, The velocity form is suit for the system which’s load change is slow like temperature control system, and positioning form is useful for system which’s load change is fast.

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