Error -70006 when using stepper motor in Open Loop Mode

[phylament]

We have a LabView program that runs a test in which a table is rotated. At the end of the test, the table is supposed to rewind. Instead, the following message appears:

Error -7006 occurred at Read Trajectory status.flx
Possible reasons: For FlexMotion, an invalid axis number or other resource ID (Vector Space, Encoder, I/O Port, and so on) was used.

We have the PCI-7344 interfaced with a UMI-7764 and a Zeta4 that is controlling a ZETA83-93 stepper motor. There is no encoder in the system for this motor. The stepper loop mode was originally set to closed loop but the motor behaved erratically (moving multiple times when instructed by MAX to move once). The stepper loop mode was changed to open loop and the m
otor started behaving properly, but that is when the error message starting appearing. Are there any other configuration settings, such as Primary Feedback (which is now set to Encoder) or ? that I may need to correct to resolve this error?

[algames]

First of all I would check a couple of things. The reason why your motor was not behaving properly in closed loop stepper configuration is most probably related to the fact that you don't have the encoder counts per revolution adn the stepper steps per revolution properly configured for your motor. Please follow the instructions found in the following knowledgebase:

http://digital.ni.com/public.nsf/websearch/29edb56146f274a386256a1c00624310?OpenDocument

When you configure an axis in closed loop stepper mode, we use the information of the encoder to generate the adequate velocity profile. If the encoder counts and steps per revolution are not properly matched, then the motor will not execute the moves properly. What you need to do is the following:

1.-Configure your axis as closed loop stepper in the Axis Conifguration Section in MAX.

2.- In thbe 1-D Interactive Basic panel, kill the motor and click on reset position.

3.- Manually rotate the motor one revolution.

4.- In the advanced panel on 1-D interactive, read the Encoder Value. This is the value you should enter on the Axis Encoder Counts per Revolution under Axis Configuration. Press Apply.

5.- Go back to the 1-D interactive Basic Panel. Change the bullet selector unbder Stepper Loop Mode from Closed to Open. Run a 10000 step move.

6.- When the move is finished, read the encoder counts from the advanced panel. This will tell you how many counts you have in 10000 steps. You can now calculate the stepper steps per revolution by the following formula:

(# of steps per count)*(# counts per revolution) = # steps per revolution.

Your motor should work fine in closed loop stepper configuration now and the error should not appear. Please make sure you are using the latest version of our driver (Ni-Motion 6.0.1)to avoid older firmware errors and fixed bugs from affecting your system. You can get it from:


http://digital.ni.com/softlib.nsf/webcategories/85256410006C055586256BB9002C16DF?opendocument&node=132070_US