Encoder selection issus

[Victor888]

Hey my friend

I was a Ti DSP developer before & I finally give up all the painful days with DSP development

Now I mainly focus on system integration

Here is what I got...just plan for a new start up

Motor-> Panasonic Mines-A Driver with 100W AC Servo

 NI PCI-7390, 4-axis position command motion controller with isolation 

problem>     Which model of motion interface connection board and cable for the Panasonic I need?

Problem 2> Which encoder is good for the controller to use? (I need the exact position with ball screw)

I need to get them right since I need to sync it with my vision

Please give me a hand.

Thanks

[Brian_Beal]

There are a few different ways to use that drive.  You can give it step and direction pulses from a stepper controller and let the Minas close the loop.  Another way is to use it in torque mode and use a servo controller to close the loop.  Either way, the Minas is the only device that sees the encoder, and you may not any choices as to what encoder comes with the motor(other than incremental or absolute).  The Minas has a simulated encoder output, but I couldn't find any specs on it.  I would assume that it is standard differential output at 5VDC.  That is what gets wired to your controller.  There would be no standard cabling between the Minas the the 7390.  You will have to choose which interface you would like to work with.  Perhaps someone from NI can give you better advice on that.

[yaHeard]

Hello,

National Instruments offers an adapter to connect the PCI-7390 to Panasonic Minas A drives.  It is called the NI MCA-7790.

[Victor888]

Got it buddy,

Looking forward to purchase the NI goodies today..

[buckmeister]

In regards to your encoder resolution, You should start with your desired mechanical accuracy needed. What distance does your stage connected to your lead screw move in one shaft rotation. This distance can be divided by your encoder line resolution to arrive at the distance moved per line. Keep in mind, that a quad. encoder out puts 4 counts per line which give 4 times the digital feed back. You should also determine if the ball screw has the needed backlash specs. to meet your demand. This can be compensated with software. A 1000  line encoder mounted to a lead screw with 5 leads per inch, can divide an inch into 20,000 parts. This is your maximum electronic resolution, which is limited by mechanical factors. I'ts been my  experience, that you should not choose a encoder, which has too many counts. This can cause tuning and stability problems. as well adding overhead to your software.