text: <s>[INST] powerflex 700 error F 90 I have a powerflex 700 series B firmware 6.004. I am trying to connect an encoder to watch the position of the motor. I set P53 (motor control select) to sensorless vector and I also tried FVC vector. I had P80 (Feedback Select) set to encoder and P412 (motor feedback type) to quad check and then to quadrature. With any of these settings I get fault 90 after a few minutes of running. So, then I set the drive back to factory defaults and i still got fault 90. I had to power down and remove the encoder card in order to run the drive without faulting on F90. Any suggestions? The encoder is new - quadrature 600 ppr. (I did set P413 to 600) Also do you know if there are any advanced drives classes available from Rockwell? [/INST] Manual report this as Encoder Quad Err, Both encoder channels changed state within one clock cycle. Actions: 1. Check for externally induced noise. 2. Replace encoder. After these two checks, I guess you may have a faulty Encoder Card... :smileysad: - fuzzy logic \\n </s>