I bought an variable frequency drive before
Let me know the answer to my technical question.
I want to know how to give pressure set point in your VFD once you activate the PID.
Which parts show this setting in the drive's user manual.

Here is the way to set it:

Regarding the pressure set point issue, please refer to parameter P7.02 and P7.14 of the user manual for pressure setting. For example, if the measure range of your pressure sensor is 10kg, and you wanna set 4kg as the feedback point, you just need to set P7.02 to 40.

The variable frequency drive can provide DC 24V and 12V (Terminal 10V max voltage when open is 12V) for the pressure sensor, but can not provide 15V. Maybe you can use 12V for your pressure sensor.

Hope it helps

Both issues sorted thank you.
However i came across across another issue.
I am planning to switch on two pumps at two different frequency. One at 45Hz the other one at 50HZ . The variable frequency drive is connected to one pump which will be operating under PID condition. When this VFD pump reach 45HZ it should switch on the second pump, when this variable frequency drive reach 50Hz it should switch on the third pump.

Let me know which parameters I have to use to set switching frequencies for the VFD.

relay TA TC terminals are normally open contacts, have a try to connect relay 1