In order to use the PID Tuner successfully, a couple of requirements must be satisfied.

Firstly, the PID Tuner must be installed on a windows based computer, and it must be able to communicate with your control computer (or simulation software) via OPC as an OPC client. In particular, the PID Tuner must be allowed to read and write certain tags in the control computer. Figure 1 shows exactly which tags. Note that the signal ‘PMV’ is added to the PID output in the control computer. This signal is used by the PID Tuner to make step experiments. You may also want to program a switch in the control computer that allows / refuses the PID Tuner (or any other OPC client) to write the signals as mentioned here (PMV, Kp, Ti, Td).

Figure 1 Block-diagram of the PID controller and the signals that the PID Tuner must be able to write and read via OPC (writable tags are shown in blue). PV = Process Variable, MV = Manipulated Variable, Kp = proportional gain, Ti = integral time, Td = differential time.

One setup that works is shown in Figure 2. In this setup, the PID Tuner software runs on the same PC that is used to program the control computer (PLC or DCS). The OPC server also runs on this PC. Other configurations may work as well.

Figure 2 Schematic representation of a PID Tuner implementation