Need to select set point of Minimum/Maximum Pressure through MFD.

[hinddhindsa]

Hi, Friends doing a program of moeller easy 820-dc-rc plc with MFD-80-B + CP4 HMI display. i need to give the set points in HMI for Cut in and cut of Pressure at 2 bar and 4 bar(it should be changeable, the operator might set maximum pressure at 5 bar or 6 bar according to the requirements).where the values are stored which we enter through HMI,How to do some mathematical operations based on that HMI Value.

 

[BryanG]

No special maths required just use the A - Analog Comparator instruction, screen shot 1.

In the second screen shot:
MW96 is your input scaled to your units (Bar), though because the MFD doesn't have floating point maths you will have to use say 100 internally to represent 1Bar.

MW1 is the SetPoint. Assuming you have used 100 to represent 1 Bar, you have to do the same for the SetPoint, so 5Bar set on screen would be scaled to 500 internally for the MFD.

HY is the hysteresis. Depending on whether you use 'Greater Than' or 'Less Than' changes how the hysteresis works but lets take a typical case. You set Hysteresis to 0.5Bar (which translates to 50 internally to MFD), as the pressure rises it would switch Off at 5Bar and switch back on at 4.5Bar.

Leave F1 and F2 at zero or set then both to 100.

Have a play and let us know how it goes.