Lineair motion control advice

[Sjoerd1973]

I hope someone can advice me.

We build a lineair setup with a 2 phase steppermotor , quadratic encoder, micro step driver with pull/dir/ena en two end switches.

In the application we have to stop at 3 specific points for a short time (1 second) and one rest position. At one position another task ( switch on/off) should be activated.

We thought we could controll this with a pci-6220 M-daq but as starter with Labview I couldn't get it to work. Spent some time on it but I coul only get the encoder to work.

I think it is not not possible to combine al the functions with this card or I'm a wrong ?

Is it easier to buy an other card like the PCI-7332 and is there a simple way to program this in labview ? Softmotion ?

[Jochen]

The application that you describe can be solved easily with a PCI-7332 and NI-Motion (the driver and API that comes with the PCI-7332). A DAQ board like the PCI-6220 is not a good fit for a motion control application as it doesn't provide features like trajectory generation (position and velocity profile) and limit switch monitoring.

The NI-Motion API in LabVIEW is very easy to use, as a lot of functionality is done by the motion board itself (trajectory and step generation, limit switch and following error tracking,...). A one axis-move with position monitor and user selectable values for target position, velocity, accleration and deceleration looks as simple as that:



If you are looking for a solution that minimizes the amount of programming required for your application to a value very close to zero, please have a look at the NI Motion Assistant. This is a tool that allows you to configure and test your motion application step by step in an interactive graphical environment. In a next step NI-Motion Assistant can create LabVIEW code from your configured motion sequence that you can use as a base for your application development in LabVIEW. NI-Motion Assistant is included as evaluation version with NI-Motion.

Best regards,

Jochen Klier
National Instruments

Message Edited by Jochen on 08-24-2007 03:52 PM

[Sjoerd1973]

Thanks. I was on the wrong track with the pci-6220.

I just installed the virtual motion drivers and the motion assistant. It looks quite simple just put in a find home, reset counters and ad my steps and wait positions . I noticed I can put the wait stage with a timer or a keystroke this is very promissing.

I have two other question. I'm reading the manual but just to be sure.
First. Can I connect the end switches, just an on/of switch without any other electronics to the pci-7332 motion control ?
Second. The microstep driver has it's own power suply what leaves me with the 3 signals + and - from the pul, direction and enable can i connect thes also without any other hardware to the motion control card ?

This is my microstepdriver
http://www.stappenmotor.nl/Datasheets/microstapdrivers%20info/MSD-50-5.pdf

[Jochen]

1. The limit switch inputs are internally pulled up to +5V and provide direct connectivity for mechanical limit switches (just connect the switch between the limit switch input and GND).
   
   
2. You can connect the motion signals of the 7332 directly to your drive. Connect the STEP output to the PUL input, DIR output to the DIR input and the INHIBIT output to the ENA input.
   

Jochen

[Sjoerd1973]

Thanks again.

One last question. I have a PC with the 6220 card . This is an AMD athlon 2400 - is says  1.83 Ghz an 512mb memory by system with windows xp, last version of labview and ni motion. Not very quick but is it enough to run ni motion ?

Gr Sjoerd

[Jochen]

As the NI-Motion board does the biggest part of the motion control task onboard, it is highly independant from the performance of the host PC. I don't see a problem running NI-Motion on your existing PC.

Jochen

[Buechsenschuetz]

The limit switch inputs are internally pulled up to +5V and provide direct connectivity for mechanical limit switches (just connect the switch between the limit switch input and GND).

You also have to check whether the limit switches you are using are closed or open when activated. You will have to set the polarity of limit switches inputs accordingly: active low if the switches are closed when activated, active high when they are opened when activated.

If your limit switches and/or set up provides a choice between the two modes of limit switch operation I would recommend the "opened when activated" option (or wiring scheme). This will provide an active limit switch signal when one of the wires breaks or when a connector is faulty. In this case the drive will not move any more towards the direction of the faulty limit switch. In "closed when activated" mode a faulty wire connection cannot be detected, i.e. the limit switch will be ignored in case a wire breaks.

[Sjoerd1973]

That's good to hear, a ne pc was not on the budget list.

Thanks for al the tips and advice.

I will set the limit's as normally closed than.

So l go ahead and start the order for a New PCI 7332 motion controller.

Gr Sjoerd

[Buechsenschuetz]

PC speed is not essential for operation of the NI boards. Our customers run NI motion control systems on a wide variety of PCs, the slowest (and oldest) systems probably have 1.5GHz or less. The motion control runs perfectly on all these machines. Of course there is a speed difference for other control programs, i.e. if you write your own software for the NI systems, but the control systems themselves are almost independent from host computer speed.

[Sjoerd1973]

Help.

The advice from NI was to go for a NI-PCI-7344 motion controller. WHY ?? Is not clear to me.

I think tha a 2 axis controller is more than enough. I only have one stepper and one direction of movement so that would mean a NI-PCI-73x2.

What is the difference between the NI-PCI-733x and the NI-PCI-734x  motion controllers ? Faster and more accurate ? but what does this mean ?

Thanks again.