text: <s>[INST] PowerFlex 755 w/CIP Motion - position error held to zero Summary: Servo loop will only run with velocity feed-forward, but will not move at any value of Kp. Environment: Drive - PowerFlex 755, 8A Normal Duty, Stardard Motor - Toshiba – Vector Duty, 3Hp,1800,182TC,TENV,230/460V/60Hz PLC - ControlLogix 1756-L72 r19.01 Comms - 1756-EN2T r4.1 Encoder - BEI XHS35F-62-R2-SS-4096-ABZ-28V/V-SM18 Encoder card in drive - 20-750-ENC-1 (Standard) configured to AqB Gearbox - Rex Planetary Mercury. Direct coupled, Ratio 20.45:1 Load/Inertia - Motor and gearbox only. No external load for test period. Linear application - Max velocity 5 Ft/Sec max. Max Acceleration 40 Ft/Sec^2 Max Jerk 400 Ft/Sec^3. Axis configured as a Position Loop. Problem After getting encoder working and removing non-allowed option board. Neither axis or drive have errors. After AutoTuning, suggested tuning gains are accepted (Position Bandwidth=3.69 hertz, Velocity Bandwidth 14.57 hertz). Issuing MSO closes loop, and puts drive into Running. Issuing MAJ causes normal running. Encoder feedback indicates motion in proper direction. MAS stops motion. Issuing MAM (Incremental 5 Ft. Vel 3.0 Ft/Min Accel 40 Ft/Min^2) causes motion planner to generate a profile. When graphed on CLx trend, commanded position, velocity, accelleration look correct. Commanded Position show ramp, Commanded Velocity is trapezoidal. Actual position remains unchanged. Actual Velocity remains unchanged. Position errror remains zero throughout move profile. Modifying tuning parameters to include Velocity Feed Forward (100%) and reissuing MAM descibed above causes motion. The Motion Planner generates profile as described above. Actual Position moves to follow Commanded position, but with error. Actual Velocity approximates Commanded Velocity, but lags in time and rings badly. Most notably, no Position Error is calculated (or at least isn't displayed). Without a Position Error to act upon, Kp & Ki are ineffective. I tried several manual settings for Position Bandwidth, up to 30 hertz. without improvement. Effectively, the PI regulator in the drive is open loop. While observing the drive's position regulator diagram through Connected Components Workbench, I issed a MAM for a 15 ft. incremental move at 0.5 ft/sec. (longer in duration to watch the regulator work). No position error was generated. Also noted that Position Command [P723] didn't change at any point through the MAM execution. A note in the diagrams says When position control is inactive, Position Command [P723], Position EGR out [ P815], and Position Load Actual [P837] get loaded with Position Actual [P836]. This seems to point to a possible reason for 0 position error, as Psn Command sums with Psn Fdbk [P847] in the Position Feedback Scaling Block to generate Psn Error [P835]. I can't find a diagram showing what conditions contribute to position control being rendered inactive. All of the bits with Position Control [P721] are axis-controlled. I find nothing in the axis parameters that indicate how they're controlled. None of those bits explicitly say position control anyway. I find myself without a way to know when position control is active and when it's not, and no diagram to show the logic of it. [/INST] Here's some addition info, in the form of the regulator diagram (snapshot). \\n </s>