8.3 Parameter Settings for Fully-closed Loop Control8-178 Fully-closed Loop Control8.3.2 Sine Wave Pitch (Frequency) for an External EncoderSet the number of external encoder pitches per motor rotation to Pn20A.Pn20A is the speed conversion coefficient when the external encoder is used as speed feedback.(1) Setting ExampleIf the external encoder is connected directly to the motor, the set value will be 1500 (30 mm/0.02 mm = 1500).Note 1. If there is a fraction, round off the digits below the decimal point.2. If the number of external encoder pitches per motor rotation is not an integer, there is some error in the speedloop. This is not relevant for the position loop however, therefore it does not interfere with the position accuracy.(2) Related Parameter8.3.3 Setting Encoder Output Pulses (PAO, PBO, and PCO)Set the position resolution to Pn281. Set the number of phase A and phase B edges.(1) Setting ExampleIf the output of a single pulse (multiplied by 4) is 1 μm, the set value will be 20.If the output of a single pulse (multiplied by 4) is 0.5 μm, the set value will be 40.The encoder output pulse will have the following waveform if the set value is 20."↑" shows the edge position. In this example, the set value is 20 therefore the number of ↑ is 20.Note: The upper limit of the encoder signal output frequency (multiplied by 4) is 6.4 Mpps. Do not set a value that wouldcause the output to exceed 6.4 Mpps. If the output exceeds the upper limit, the overspeed of encoder output pulserate alarm (A.511) will be output.Example:The frequency is as follows if the set value is 20 and the speed is 1600 mm/s:= 1600000 = 1.6 MppsBecause 1.6 Mpps is less than 6.4 Mpps, this value can be used.SpecificationsExternal encoder sine wave pitch: 20 μmBall screw lead: 30 mmPn20ANumber of External Scale Pitch Classifica-tionSetting Range Setting Unit Factory Setting When Enabled4 to 1048576 1 pitch/rev 32768 After restart SetupPositionSpecificationsExternal encoder sine wave pitch: 20 μmBall screw lead: 30 mmSpeed: 1600 mm/sPhase APhase BSine wave pitchRotation1600 mm/s0.001 mm
