How can 2 encoders be connected (mapped) to 1 axis in a UMI-7764 for dual-loop encoder feedback?

[kevlar]

The NI-Motion user manual says that dual-loop encoder feedback can be enabled by mapping a load sensor as the primary feedback for the axis and mapping the motor sensor as the secondary feedback for the axis.  How can both encoders be connected to the same axis when the UMI-7764 only has connection termianls for 1 encoder per axis?  My system consists of an Exlar SR-21 servo motor linear actuator with rotary encoder, a Microsyn external linear encoder attached to the load, an Emerson EN-208 servo drive, a UMI-7764, and a PCI-7342.  For software I'm using NI-Motion 7.2 and LabVIEW 7.0.

Thank you for your help.

Kevin Hanson

[s_a_s]

Kevin,

All you will need to do is to set the encoder feedback in MAX to Dual-Loop Encoder.  The feedback will then show which encoders are assigned to be used for your feedback.  You can then connect the proper terminals on the UMI-7764.  In the case of the image I've attached, encoder 1 and 3 are being used for my dual-loop feedback - this will be the same for your system (7342) as it is for my system (7344) because even though you have two activated axes for motion control you will still have access to all 4 encoders. 

Let me know if you have any questions.

Message Edited by s_a_s on 04-14-2006 03:43 PM

[kevlar]

SAS:

Yes, I've seen that when I enable dual-loop encoder feedback in MAX that it shows configuration pages for encoders 1 and 3.  When you say that this tells me which terminals to connect in the UMI-7764, does that literally mean I should connect my primary encoder (the load sensor) to the axis 1 encoder terminals and my secondary encoder (the motor sensor) to the axis 3 encoder terminals?  I guess this was just too obvious for me to see.

Thanks again for your help,

Kevin Hanson

[s_a_s]

Kevin,

You are right on target.  Connect your primary encoder to the input for the encoder on axis 1 and your secondary should be connected to the encoder input for axis 3.