text: <s>[INST] Powerflex 700 PI control....Help needed Hi I am new to the forums, I hope I'm in the right place to get some help.I have an application using a 110 Kw powerflex 700 inverter (vector) driving a 90kw motor being used as a pump (PD not centrifugal). I have a pressure gauge sending me a 4-20 mA signal which I am using as my speed control method (I am also using a pot on the panel as my 2nd analogue signal for manual control. Currently I am using the pressure gauge from 3 Bar (4mA) to 11 Bar (20mA) and I want to keep the pressure at 11 bar but of course I accelerate at the start and slow down as I get to 11 Bar but once I am at speed at 20 mA the pressure keeps creeping up over 11 Bar and I have no way of slowing the motor down to reduce the pressure. I think (please feel free to correct me if I am wrong) that a better method would be to use the PI control function in the inverter. My problem is I could really do with some help in knowing which parameters I am concerned with for this application. I am hoping (probably naively) that I can set my speeds and a reference to the pressure (in mA) and the inverter will do the rest. I would really like to know how to get this application running and also would like to learn more about this for future applications but I am a bit of a novice so can someone please supply me with a solution in the form of a idiots guide (for an idiot !) Anyone and everyone's help would be really appreciated Dan [/INST] Hi Dan,Yes, PI control is what you want to do. You want to use the PI in Exclusive mode. Parameter 124 sets this up. Set bits zero and four. Exclusive mode means that we are doing standard PI and not speed trim. Zero clamp means that if the PI algorithm results in a negative value for the reference, the drive will clamp the reference at zero stopping the motor, not reversing it. Then, parameter 125 enables the PI system to work. Set bit zero. Now you have your choice of where to adjust your setpoint. Most people use the PI Setpoint (which is parameter 127), but you can use one of the other inputs if you wish. I suggest using the PI Setpoint for now. Parameter 126 is set at PI Setpoint by default. Parameter 128 is where you select the feedback input. You'll choose the analog input where your transducer is connected now. I recommend also setting the accel and decel values to about 2 seconds and let the PI control the rate of accel and decel. Those are parameters 140 and 142.Since the PI Setpoint in parameter 127 is set to 50%, the drive will do whatever it needs to do to drive the feedback to 12mA which is 50% of the 4-20mA range. Larger values for the PI Setpoint will cause the drive to ramp the motor faster to null the setpoint / feedback error. Smaller numbers will do the opposite.The PI Prop Gain parameter 130 is set to 1.0 by default. This means that for every 1 percent change in error between the setpoint and feedback, the drive output will change 1 percent. Smaller numbers here make the output of the drive less active, larger numbers make it more active. Try the defaults for params 129 and 130, they usually work well as a starting point. \\n </s>