[andypugh]

If the AD converter gives 12-bit analog control output (in the range of 0 - 10 V), and 10 V is corresponding to exactly 360 degree rotation, I would expect similar position resolution for analog control in position mode.

Yes, but if you set it up so that 10V == 360 degrees you can only turn the motor one revolution, so can only move 5mm total. If you change the gearing (physical or electronic) so that you can travel the full length of the 1000mm screw then that is 200 full revolutions, so your resolution-per-bit is 200x worse.

I will point out that analogue-input position servo mode is a very uncommon way to drive a motor. It would allow you to use a potentiometer to rotate a remote actuator, but that seems an expensive way to have a cheap command source.

[mactec54]

Yes, but if you set it up so that 10V == 360 degrees you can only turn the motor one revolution, so can only move 5mm total. If you change the gearing (physical or electronic) so that you can travel the full length of the 1000mm screw then that is 200 full revolutions, so your resolution-per-bit is 200x worse.

I will point out that analogue-input position servo mode is a very uncommon way to drive a motor. It would allow you to use a potentiometer to rotate a remote actuator, but that seems an expensive way to have a cheap command source.

It does not work like that,

Also analog systems have been in use for CNC controls, since the beginning of time, for machine servo motor controls, and are still used in most machines today

If 10v was applied to the servo drive it would run at max speed, until it was told to stop, which would be Zero Volts at stop,10v does not mean or equal 360 deg,and would not be used like this in any analog/servo system

The traditional analog drive, the desired motor velocity is represented by an analog input voltage usually in the range +/-10 volts. Full forward velocity is represented by +10v and full reverse by -10v. Zero volts represents the stationary condition and intermediate voltages represent speeds in proportion to the voltage.

[andypugh]

It does not work like that

I did say that it would be unusual, but it is a control mode available with the Dyn4 and seemed to be what the OP was proposing to use.

If 10v was applied to the servo drive it would run at max speed, until it was told to stop, which would be Zero Volts

In analogue velocity mode, yes. But the Dyn4 drive has analogue modes for torque, velocity _and_ position.

For a CNC machine analogue velocity is probably the one to use. I think this has advantages over digital (step/dir) position mode in that you can take advantage of feedforward in the control PC.

[mactec54]

I did say that it would be unusual, but it is a control mode available with the Dyn4 and seemed to be what the OP was proposing to use.

In analogue velocity mode, yes. But the Dyn4 drive has analogue modes for torque, velocity _and_ position.

They still operate the same way, it makes no difference what modes they are working in,

The DYN4 servo drive accepts industry standard pulse/analog commands. Pulse format include PULSE+DIR, CW+CCW, A+B Phase Quadrature. Servo control modes including Position, Speed and Torque. Standard line drive encoder output provide position feedback to host controller.

[mactec54]

I see what you are saying now,about what he was asking, that would be using a PWM control with just using 0-10v,

It is there in there manual, I had just not taken any notice of it, this could be used for spindle orientation, rigid tapping etc

Analog Input in Position Servo Mode In position servo mode, the controller can use 0 ~ 10VDC analog input to turn the motor. 0 ~ 10VDC analog input commands motor from 0 ~ 90*4,096/Gear number (degrees). Ex. if Gear_Num=8,192, a 5.5V input will move the motor 24.75degrees.

[jiuning]

That is where my question comes when I read that part.

[mactec54]

That is where my question comes when I read that part.

The main uses for this function/mode of operation, is mostly for a single programed command, for Robot positioning, it has many other uses as well, it's just another mode of operation there drives can do

[jiuning]

Yes, but if you set it up so that 10V == 360 degrees you can only turn the motor one revolution, so can only move 5mm total. If you change the gearing (physical or electronic) so that you can travel the full length of the 1000mm screw then that is 200 full revolutions, so your resolution-per-bit is 200x worse.

I will point out that analogue-input position servo mode is a very uncommon way to drive a motor. It would allow you to use a potentiometer to rotate a remote actuator, but that seems an expensive way to have a cheap command source.

Now I understand the numbers you got in the example. Everything makes sense to me now. Thanks!