Liquid pressure control with Siemens S7 300 and Yaskawa

Dear All,

I have to control the pressure of a liquid with a Yaskawa V1000 inverter. The inverter is connected with Profibus to a 317-2-DP CPU. The inverter's frequency reference is a Word (2 Bytes).
If I set "5000 decimal" in that register, then the motor runs on 50.00Hz (there is no negative value in the register).

The pressure sensor's measuring range is "0...600bar", and it has a 4-20mA output.
I have to set the pressure of the liquid in 0.1bar unit.

I think I should use FB41 (CONT_C), but I dont know how exactly.

Please help me. Thank you in advance.

Hi,
Correct me if I misunderstood.
You want to achieve an accuracy of 100mb with an analog sensor 0 ... 600b?
Where did you find this sensor 600b max range?

Hi,
Yes, I want to achieve that accuracy. It depends on the resolution of the A/D converter.
It is a Barksdale sensor. Order number: UPA2-HT-43-415991210

Could you help to set up FB41?

Ors said:

Could you help to set up FB41?

Click to expand...

Try to upload the program where you want to integrate the pid (FB41) I can take a look.

There is no program yet

We don't even know if the system will be controllable.
What is the volume of fluid that is being pressurized?
If the pump can only go in one direction then how does the pressure decrease? Is there leakage? The fluid must escape somehow or the pressure can only increase.
What is the fluid? It makes a BIG difference because some fluids are more compressible than others.
What is the size of the pump? How many cc per rev?
What kind of pump?
Does the pressure signal go to the drive or the PLC?

Forget about the PID for now. If the system is designed right then getting the PID to control will be easy.

There is a formula that is key to this application.
dp/dt=B*Q(t)/V
where
dp/dt is the rate of change in pressure
B is the bulk modulus of the fluid
V is the volume of fluid being compressed
Q(t) is the net flow in or out.
dp/dt can be very high even with small flows. If dp/dt is too high then controlling pressure will be difficult unless the scan time is in the millisecond range. If the volume of fluid being compressed is big you still might have a chance.