Specifications
11– 4
11.SELECTION
The servo motor is run at a speed where the command pulses and feedback pulses are equivalent.
Therefore, the command pulse frequency and feedback pulse frequency are equivalent. The relation
including the parameter settings (CMX, CDV) is as indicated below (refer to the following diagram):
fo •
CMX
CDV
= Pt •
No
60
..................................................................................................... (11-4)
fo : Command pulse frequency [pps]
(Open collector system)
CMX : Electronic gear (Command pulse multiplication
numerator)
CDV : Electronic gear (Command pulse multiplication
denominator)
No : Servo motor speed [r/min]
Pt : Number of feedback pulses [pulses/rev]
(Pt = 8192 for HC-MF)
According to Equation 11-4, the following equations may
be used to obtain the electronic gear and command pulse
frequency to rotate the servo motor at No.
• Electronic gear
CMX
CDV
= P •
No
60
•
1
fo
................................................................................................................... (11-5)
• Command pulse frequency
fo = Pt •
No
60
•
CDV
CMX
................................................................................................. (11-6)
[Setting example]
Obtain the command pulse frequency required to run the HC-MF at 3000r/min.
When the electronic gear ratio 1 (initial parameter value) is used, the following result is found
according to Equation 11-6:
fo = 8192t •
No
60
t •
CDV
CMX
= 8192t •
3000
60
t • 1
= 409600[pps]
However, as the maximum input command pulse frequency in the open collector system is
200kpps, 409600pps cannot be entered.
To run the servo motor at the speed of 3000r/min at not more than 200kpps, the electronic gear
setting must be changed. This electronic gear is found by Equation 11-5:
CMX
CDV
= 8192 •
3000
60
•
1
200 x 10
3
=
256
125
Therefore, the parameters are set to CMX=256 and CDV=125.
11-3 Speed and command pulse frequency
Electronic
gear
Servo motor
Feedback pulse
frequency
fo
CMX
CDV
(Command pulse frequency)
(Electronic gear)