Hi all,
Using a powerflex 525 with a quadrature encoder for the first time. The application is to track product movement along a belt from a metal detector to a reject point. The PF525 is connected to a GuardLogix PLC using the embedded ethernet port, so I want to try to get the speed feedback data over that link.
I've read through the manual and think I have my head around how it works, but the manual gives me a few options for the encoder setup and I'm not sure which is best for my application...
I feel that option 1 is the simplest, but I'm not sure if it actually does what I want - if not I guess I'm looking at option 3. Any tips?
Using a powerflex 525 with a quadrature encoder for the first time. The application is to track product movement along a belt from a metal detector to a reject point. The PF525 is connected to a GuardLogix PLC using the embedded ethernet port, so I want to try to get the speed feedback data over that link.
I've read through the manual and think I have my head around how it works, but the manual gives me a few options for the encoder setup and I'm not sure which is best for my application...
If I understand correctly, this method would mean that I can either give the drive a speed reference via pulse train, or give it a position reference and have the drive go to that position using the encoder as position feedback. Neither of these are what I want - can I give the drive a speed reference and have it go to that speed using the encoder to confirm speed feedback? I'm not sure whether "normally used with a quadrature encoder" and "normally used with a pulse train" should be taken to mean "that's the standard but other options are available" or "that's really the way to do it, if you try to do it any other way you're doing it wrong".1. If enabled by P047 [SpeedReference1], the encoder or pulse train will be used directly as a commanded speed (normally used with a pulse train) or as a position reference (normally used with a quadrature encoder).
I don't think this is what I need - a PID speed loop seems way overkill for this. I just need to know an accurate belt speed.2.If not enabled by P047 [SpeedReference1], when the PID Feedback or PID Reference are set to use an encoder then the PID function will use the encoder or pulse train input.
This one seems like it might be what I'm after. If I understand correctly, I will give the drive a speed reference of, say, 47.5Hz, and it will run at whatever frequency is required to make the encoder input match the 47.5Hz command. Am I right so far? If so, I guess that just means I will have to tune up parameters A538 and A539 to give consistent speed control. How would I go about this? Is it just a matter of commanding rapid speed changes and massaging the values until I get a smooth response? Or is there a more "scientific" approach I could take?3.If not enabled by P047 [SpeedReference1] or the PID parameters, then if A535 [Motor Fdbk Type] is set the encoder or pulse train is used for direct feedback and trim of the speed command. The normal slip compensation is not used in this case. Instead the drive will use the encoder or pulse train to determine actual output frequency and adjust the output frequency to match the command. Parameters A538 [Ki Speed Loop] and A539 [Kp Speed Loop] are used in this control loop. The primary benefit of this mode is increased speed accuracy when compared to open-loop slip compensation. It does not provide speed bandwidth improvement.
I feel that option 1 is the simplest, but I'm not sure if it actually does what I want - if not I guess I'm looking at option 3. Any tips?