Panasonic MINAS-A4P Technical Reference

No. SR-DSV09485 - 105 -A4P MOTOR COMPANY, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD[1] Setting of external scale ratioSet up the external scale ratio using the numerator of external scale ratio (Servo parameterNo.78), the multiplier of numerator of external scale ratio (Servo parameter No.79) and thedenominator of external scale ratio (Servo parameter No.7A).- Check the number of encoder pulses per motor rotation and the number of external scale pulsesper motor rotation, set up the numerator of external scale ratio (Servo parameter No.78), multiplierof numerator of external scale ratio (Servo parameter No.79) and denominator of external scaleratio (Servo parameter No.7A) so that the following formula is fulfilled.- If the ratio is incorrect, the difference between the position calculated from the encoder pulse andthe position calculated from the external scale pulse is increased. Particularly, when it is driven along distance, a hybrid deviation error (Err.25) occurs.- When Servo parameter No.78 is set to 0, the encoder resolution is automatically set to a numerator.[2] Hybrid deviation error setupSet the hybrid deviation error level (Servo parameter No.7B) to the minimum value within the rangewhere the difference of a position between a motor (encoder) and a load (external scale) can beconsidered excessive.- As for the hybrid deviation error (Err.25), make sure to check its reason carefully as it also occurs due toa reason other than that stated in the above item (1), such as the reverse connection of an external scale,the loosened connection between a motor and a load, etc.Precautions(1) Input position command on the basis of an external scale.In the full-closed control mode, the encoder is used for the speed control and the externalscale is used for the position control.(2) External scales, which can be used for the full-closed control, are as listed below.- AT500 series made by Mitutoyo Corporation- ST771 series made by Mitutoyo Corporation(3) To prevent the breakage of a machine due to excursion based on the setting of the above externalscales, set the hybrid deviation error level (Servo parameter No.7B) to a proper value in units ofexternal scale resolution.(4) For an external scale, the value of 1/20 ≤ External scale ratio ≤20 is recommended.If the external scale ratio is set to a value less than 50 / Position loop gain (Servo parameterNo.10, 18), its control per pulse may become impossible.The larger the external scale ratio is, the bigger the operation noises may be.Pr.78 1 x 2Pr.7A 5000Pr.7917Number of encoder pulses per motor rotationNumber of external scale pulses per motor rotation