Controlling step motors with UMI-7774

[Maître]

I need to control two step motors via an UMI-7774. Everything is connected, but all the axes are disabled (LED is on). I have no idea on how to enable my axes and control my motors. I tried following the steps in the Mesaurement and Automation Explorer Help for Motion, but I get an error message saying the desired move cannot be completed because the limit input is active in the direction of travel (error-70119). Please help me!

[Jochen]

This error typically occurrs if the polarity of your limit switches doesn't match the settings in MAX. This might also happen when no limit switches are connected. Please check your cabling and invert the limit switch polarities in MAX if required.

If this doesn't solve the problem please provide more information about your system setup (Which NI-Motion board are you using (73xx)? What's your driver version?)

Best regards,

Jochen Klier
National Instruments Germany

[Maître]

Exactly what are limit switches? Is it something I must physically plug in the UMI-7774?

I am using the PCI-7334 as the stepper controller. I have LabVIEW 8.0 and version 1.3 of Motion Assistant.

I have tried several things, but I cannot get rid of the disabled LED of the axes.

Thanks a lot!

[VuD]

Hello Maitre,

A limit switch is a device that produces a signal used to halt the motor. Limit switches are usually used to indicate an end of travel, or to prevent a motor from travelling too far in one direction. You can find more information regarding limit switches here.  In regards to wiring the limit switch, you can find this information in the UMI manual on page 42.  Have you tried just resetting (under the status tab) and reinitializing your board in Measurement Automation Explorer?  I hope this helps.  Please let us know if you would like further clarification. 

Regards,

Vu D