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How can PMAC know that what a speed 1V means?
#1
Hello, everyone, here I come again~

I am using Turbo Pmac2 Clipper to control Fuji Servo systems,

and I set it to work in the analog mode.

So the PMAC gives out an analog voltage command which present a rotation velocity

but you see that the command in a motion program has the unit of counts/msec,

So how can PMAC know that what a speed 1V means?

Or How can PMAC know that what a voltage should output when receive a speed command in the unit of cts per second?

thank you for your attention~
#2
PMAC doesn't know and doesn't care about the relationship of volts to speed(or torque). It will adjust the analog signal to match the commanded position. All scaling of what the analog signal means is done in the drive. PMAC is blind to the scaling, and whether the drive is in torque or velocity mode.
#3
BUT, DO N'T YOU THINK THAT IT WILL RESULT A LONG DYNAMIC PROCESS AND A BAD RESULT FOR A TRAJACTORY FOLLOWING?

(08-01-2011, 08:33 PM)KiraYamato Wrote: Hello, everyone, here I come again~

I am using Turbo Pmac2 Clipper to control Fuji Servo systems,

and I set it to work in the analog mode.

So the PMAC gives out an analog voltage command which present a rotation velocity

but you see that the command in a motion program has the unit of counts/msec,

So how can PMAC know that what a speed 1V means?

Or How can PMAC know that what a voltage should output when receive a speed command in the unit of cts per second?

thank you for your attention~

(08-02-2011, 04:16 AM)Brian Wrote: PMAC doesn't know and doesn't care about the relationship of volts to speed(or torque). It will adjust the analog signal to match the commanded position. All scaling of what the analog signal means is done in the drive. PMAC is blind to the scaling, and whether the drive is in torque or velocity mode.

#4
No. That is the way it has always worked, and it works very well. Direct PWM is better, but analog still works well.
#5
So, you mean that PMAC never knows how much rpm 1 V means, and how many counts one rev generate?

(08-02-2011, 06:57 AM)Brian Wrote: No. That is the way it has always worked, and it works very well. Direct PWM is better, but analog still works well.

#6
That is correct. If you use the motor in a coordinate system, then you can scale counts to real world units, but as far a PMAC is concerned, it only looks at counts.
#7
Thank you for your explanation. By the way,my Turbo PMAC works in PWM mode, it give the amplifier a analog voltage signal as a velocity command, so PMAC also look at counts only?

(08-02-2011, 07:20 AM)Brian Wrote: That is correct. If you use the motor in a coordinate system, then you can scale counts to real world units, but as far a PMAC is concerned, it only looks at counts.

#8
The Clipper has can work in direct PWM mode, but your amplifier has to be compatible. It sounds like your amplifier is traditional analog. The Clipper doesn't have true DACs, but produces a PWM signal that looks like an analog signal to most amps. Be sure to set your frequencies correctly(in the manual), or your motor will jitter and overheat.


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