Cylinder balance solutions?

I have an AB 1500 LRP with an IF4xOF2 analog card. I monitor pressure on a hydraulic cylinder with a 4-20 transducer. As cylinder pressure increases I want to oppose the load with an air pressure box supplied with a 4-20 regulator. This opposing or supporting load will be adjusted or scaled by the operator thru a Panelview.

This is an experiment so we do not know what accuracy will be required but we think we can be pretty far off and be functional.

How many ways are there to skin this cat?

PS This is not a student project.

Thanks guys

Air_PSI_CMD = Hydraulic_PSI_Actual * PanelViewValue

Nothing to regulate, so it's just a linear transfer function.

Please explain. I'm using a PV+

gas said:

Please explain. I'm using a PV+

Click to expand...

Doesn't matter what PV you're using.
Are you looking for advice on the system?
How to configure communication between devices?
How to program the PLC?

The operator enters in a scaler value on the PanelView. To make it simple, let's assume it's completely scaler and normalized (meaning an entered value of 1.0 will have no change on the output).

You scale your 4-20 input into engineering units (you'd want to do this anyway for display probably), and similarly, you scale somewhere your air pressure command in engineering units, and convert it to 4-20 only just before being sent to the analog output.

So, your Air_PSI_Command_Value is simply equal to the Hydraulic_PSI_Actual_Value times the Operator entered Scaler Value (say a range of 0 to 5).

The actual devices you are using don't matter, and I can't offer you more detail, as I have no idea of what your real process is, or the values involved.

How to program.
My first thought was to use the PID instruction that I have never used.
I always look first for a simple solution, that is why I posted here.