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PLC – PID auto-tuning function for temperature control

Users may not be familiar with a new temperature environment. In this case,  its advisable to use the PID auto-tuning functionality to improve the PID parameters settings. To do so, selecting auto-tuning (S3+4 = K3) for an initial adjustment is suggested. After initial tuning is completed, the instruction will auto modify control mode to the mode exclusively for adjusted temperature (S3+4 = K4). In this example, the control environment is a heating oven. See the example program below:

Picture 1

Results of initial auto-tuning:

Picture 2Picture 3

Results of using adjusted parameters generated by initial auto-tuning function:

Picture 4

From the figure above, we can see that the temperature control after auto-tuning is working fine and it spent only approximately 20 minutes for the control. Next, we modify the target temperature from 80°C to 100°C and obtain the result below:

Picture 5

From the result above, we can see that when the parameter is 100°C, temperature control works fine and costs only 20 minutes same as that in 80°C.

If you want to test it right away, here is the PLC program ready to download:

PID Autotining PLC program example

We hope this tool is useful for all of you and make your work better. Enjoy it !

DPIDE: Advanced PID algorithm for AH500 PLC

Delta AH500 PLC programming instructions for PID algorithm.

Instruction code: DPIDE (API 0708)

DPIDE Block description

Explanation of the DPIDE instruction:

The PID algorithm is implemented only when the instruction is executed.

PID  stands for Proportional, Integral, Derivative and is widely applied to mechanical, pneumatic and electronic equipment.

For a detailed explanation of DPIDE parameters, please refer to the following file: DPIDE Explanation

Application example:

Before the instruction DPIDE is executed, the setting of the parameters should be complete. When M1 is OFF, the MV is 0, and the MV is stored in D200. When X0.0 is switched OFF, the instruction is not executed, and the previous data is unchanged.

DPIDE Block example

The PID algorithm: When PID_MODE is set to 0 (false), the PID control mode is in automatic control mode.

When PID_MODE is set to 1 (true), the PID control mode is in automatic tuning mode. After the tuning of the parameters is completed, PID_MODE is set to o (false) automatically.

You can download the example program from here

More detailed information about PID:

PID Block Independent

PID Block Dependent

 

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