Speed And Command Pulse Frequency - Mitsubishi Electric MELSERVO MR-J2-A Product Specifications And Installation Manual

11.SELECTION

11-3 Speed and command pulse frequency

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):
CMX
N
o
f • = P •
o t
CDV
60
Electronic
gear
fo
CMX
CDV
Feedback pulse
frequency
• Electronic gear
CMX
N
o
= P • •
CDV
60
• Command pulse frequency
N CDV
o
f = P • •
o t
60 CMX
[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:
N
o
f = 8192 • •
o t t
60
(Command pulse frequency)
3000
= 8192 • • 1
t t
60
= 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
3000
= 8192 •
CDV
60
(Electronic gear)
256
=
125
Therefore, the parameters are set to CMX=256 and CDV=125.
.....................................................................................................
f
o
CMX : Electronic gear (Command pulse multiplication
CDV : Electronic gear (Command pulse multiplication
N
o
Servo motor
P
t
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.
1
................................................................................................................... (11-5)
f
o
.................................................................................................
CDV
CMX
1
•
3
200 x 10
: Command pulse frequency [pps]
(Open collector system)
numerator)
denominator)
: Servo motor speed [r/min]
: Number of feedback pulses [pulses/rev]
(P = 8192 for HC-MF)
t
11– 4
(11-4)
(11-6)