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My confusion is that what is the difference between a standalone pid controller such as the one shown in below link https://akytec.de/en/trm212.html

And a microcontroller/microprocessor programming based pid controller? Especially in terms of construction and applications?

Here is another link,where you can find a standalone temperature control pid controller

https://realpars.com/pid-controller/

I want to know that the standalone temperature control pid controller in above link is same as microcontroller programming based pid controller? Or standalone pid controller has something else instead of microcontrollers?

I am not asking for difference between analogue pid controller and digital pid controller

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    \$\begingroup\$ I don't yet understand the question. I appears to me that the link you provides is, itself, based upon a microprocessor. Then you ask how it might differ from an MCU based PID. I think you misunderstand the product you link. So there is no good answer. if you want to ask a useful question, then ask about the difference between an analog PID controller and an MCU based one. Just my ignorant opinion. \$\endgroup\$ – jonk Nov 14 at 6:17
  • \$\begingroup\$ In an PID controller the PID-algorithm is already included in the microcontroller it's your job. \$\endgroup\$ – Mike Nov 14 at 6:49
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    \$\begingroup\$ There is no operational difference. Your question is too vague. \$\endgroup\$ – Chu Nov 14 at 8:10
  • \$\begingroup\$ The link that you show is a microcontroller-based pid controller. \$\endgroup\$ – Scott Seidman Nov 14 at 13:48
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I'm not sure this is a well-posed question. Or at least, maybe I misunderstand it. I think what you're interested in is the difference between an analogue and digital PID controller.

If that is the case, the basics aren't so difficult.

An analogue PID controller uses continuous-time, analogue components such as an opamp amplifier, integrator, and differentiator for the P, I, and D respectively. Signals are manipulated in real-time, in hardware, but only at the complexity you designed into the controller. The weight of each component is controlled by a gain parameter; these gains are tuned to get the PID controller to behave as desired. See the Ziegler–Nichols method which just happens to be the method I learned/remember.

Here's the relevant bits of an analogue PID controller pinched from http://www.ecircuitcenter.com/Circuits/op_pid/op_pid.htm

Analogue PID controller

Advantages include: it's fast (lack of any processing delay), and the ability to create simple designs with few/cheap parts (at least for simple controllers.) The analysis and synthesis is typically easier than discrete-time digtal PID controllers.

Disadvantages include: being practically constrained to only a few poles, the fixed nature of hardware is not easily changed or improved later, tuning is a real pain!

A digital PID first samples the inputs using an ADC. After that, everything that is the PID controller is simply mathematics carried out on vectors of samples in a processor, CPLD, or FPGA. The continuous-time calculus breaks down into the discretised finite-differences. The math introduces a processing delay between input and output which you need to design around. Finally a DAC reverses the process to provide the continuous-time output in a process called "zero-order hold."

Here's the block diagram for your linked device. enter image description here

Advantages include: the ability to realise a high number of poles with no extra effort (at the cost of processing delay), the ability to easily change and improve the design later, easier tuning (software can sometimes even do it for you!)

Disadvantages include: introducing the processing delay which is dependant on the PID design and the processor it's running on, typically more complex/costly than a simple analogue equivalent.

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  • \$\begingroup\$ The block diagram fig6.2 in your answer does not show any processing component such as microcontroller \$\endgroup\$ – Man Nov 14 at 13:34
  • \$\begingroup\$ @Man The TRM212 is a digital PID controller. A microcontroller would perform many of the calculations in the big box, just as the TRM212 does. \$\endgroup\$ – Clipboard_Waving_Enginerd Nov 14 at 22:03
  • \$\begingroup\$ You mean trm212 contains a microcontroller?? \$\endgroup\$ – Man Nov 15 at 15:36

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