can I control motors with NI 9263%2F9265%3F

[dav2010]

Hi,

I am trying to control Maxon motors, and have been using a commercial controller that operates by accepting serial commands sent through the COM port on my PC from the Labview VI.  Labview VI easily sends the serial commands etc.  The limitation is that the serial commands are slow, and require wait times in between, or the controller does not get them.  I am operating three motors at the moment and want to expand to 5, so, that is a lot of waiting in between before I get back to update the first motor again.  So, I cannot update the motor speed as quickly as I would like.  It is taking 500 ms or so to execute once because of all the delays and the many commands I want to issue to three independently running motors. 

I need SPEED CONTROL ONLY.  Once the motors are running, I need only update the speed, with no change in direction, torque etc.  I want to update the speed as frequently as possible using DAQ.

So, I did some research, and I found the NI 9263 analog output module.  Can I connect the NI 9263 to the Maxon Escon 50_5 servo amplifier to control my motors?  It looks like the 9263 has 4 channels, so, presumably, I can send commands to four Escon 50_5’s to control four motors simultaneously.  Am I reading these right?

Or the 9264.  The only difference I see between the 9264 and 9263 is the update rate and the channel count.  Do you agree that this is the only difference?

Thanks,

Dave

[johnsold]

Dave,

That Maxon document does not appear to say that the analog inputs control the speed. Do you have other documents which indicate that it works that way?

If so, the NI 9264 might be a suitable choice.

Before buying anything check carefully on the isolation requirements to make sure that you will not have a common mode voltage or ground problem.  This is not specific to these devices but something which should be done anytime you are connecting mulitple controllers and DAQ devices together.  The power guys and the DAQ guys are not always thinking the same way about such things.

Lynn

[dav2010]

Hi Lynn,

I have confirmation from the Maxon engineer that the amplifier works by accepting a control voltage at the input and outputting appropriate power to control the motor to the desired speed.  That is the intended purpose of that device.  I am currently using motor controllers from a different manufacturer that function by serial commands.  The serial commands are very slow, and they only execute if a WAIT period is inserted in between them, so, this is undesirable. 

Do you think that the 9263 would issue the voltage commands faster from the VI that using serial commands?

Updating the motor speed at a faster rate is the only reason to consider the 9263 and the Maxon servo amplifier.  Can you offer any comment about the 9263 vs. 25ms wait times for the serial commands sent through a COM port on the PC?

Thanks,

Dave

[johnsold]

Dave,

The Maxon controller is designed to work as a servo controller so it seems reasonable that its response speed would be quick. The datasheet shows a 5.36 kHz sampling rate for the controller in speed mode. I would interpret that to mean that it samples inputs, calculates speed and setpoint, and generates outputs at that rate.  Your motor (and load) probably cannot keep up with changes that fast, but the analog input will certainly be faster than <40 Hz serial commands.

I think the analog input controller could be significantly faster than the serial port controller, but the details of the motor and load characteristics as well as the controller are factors.

Lynn

[dav2010]

Thanks, Lynn, I'll follow up with the Maxon tech service people when he returns from his vacation/leave next week, and confirm the performance expecations with him.

Dave