help S7 300

Hi, this my first time using step7, and this is, i guess, to simple for most of you here, but i don’t have any PLC programming experience.
I need to monitore water flow by setting the pump frequency manually (start the pump (frequency converter), and set it’s frequency from SCADA).
Frequency of the pump is my PLC-s analog input (with permission signal digital input), and flow is my analog output.
My question is:
Is there a FB in S7 300 i can use for this, and does anyone have an example S7 program that can help me, please?
Thank you in advance, Mark.

Mstr said:

I need to monitore water flow by setting the pump frequency manually (start the pump (frequency converter), and set it’s frequency from SCADA)

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Are you setting the pump frequency manually or via scada ?

Via SCADA.
I need to run it for few seconds in one frequency, and then i have to change frequency for couple of times, and measure the flow for each frequency.
In SCADA i will have START button and TextBox to set wanted frequency of the pump.

Use the Unscale function.
Setpoint from HMI is 0-100 hz.
That goes into the Unscale function, FC106 I think. I am not at a programming computer. The output of the Unscale function goes to your analog output to the inverter speed reference.

Program the inverter for 0-100 hz, not 0-60 hz. If you need to clamp the inverter use the max speed parameter to limit it to 60 hz. I always leave the inverter at 100 and clamp the setpoint on the few instances I run into when the motor cannot go over X hz. There are as many ways to do this as there are programmers.

In this way 0-x hz setpoint on the SCADA will be 0 - x hz on the inverter.

Thank you for answering, i did unscale for mu frequency output PQW256, and scale for monitoring flow input PIW256. I don't have PLC, i simulated it in PLCsim (i set MD 20 slider:Real, and PIW256 slider:Int- Is this ok?).
Will this work on the real PLC and, if not, what else I have to do to make it work on real PLC?

Q124.0 is my permission signal for frequency converter.