Connecting an R-Series Device to a MID-765x Drive for Servo Motor Control

If you use NI SoftMotion with a PCI/PXI-783xR reconfigurable I/O (RIO) board to control a servo motor, you will need an external power drive. This document describes how to connect the 7831R to a MID-765x servo motor drive using encoder feedback for closed loop control.

The NI SoftMotion Development Module for LabVIEW 7.1 ships with tools and example software for controlling motion via M Series DAQ devices and FPGA devices such as cRIO and the 783xR series I/O boards for PCI and PXI.

This document provides the information you will need for physically wiring a 783xR to a MID-765x servo motor power drive. This information is also useful as a starting point for understanding how to connect the other I/O devices listed above to the MID-765x or third party power drives.

Servo power drives require an analog control input, so this document does not apply to those 783xR devices that only have digital I/O.

Connecting the 783xR to the MID-765x power drive

The MID-765x power drive connector is designed to be pin compatible with NI-73xx motion control boards, so you can get a pinout listing by looking at the "Signal Connections" chapter of the NI-7350 User Manual. Similarly, the 783xR series pinouts are available in the NI 783xR User Manual .

The LabVIEW 7.1 SoftMotion example for reconfigurable I/O (Typically found at C:\Program Files\National Instruments\LabVIEW 7.1\examples\Motion\SoftMotion\RIO) require three signals per axis (AO control and encoder A/B feedback) and three common connections (AO ground, Digital ground, and +5 V) to connect the 783xR to each axis of a power drive.

For single axis applications, the MID-765x signals can be connected to the 783x as follows:


The +5V connection is used as an interlock signal that disables the power drive in the event that the cable is disconnected.

The shipping examples do no provide axis inhibit control, which is optional for MID drives. Inhibit funcionality can be easily implemented using a spare DIO line as shown above.

To control additional axes, simply connect additional 783xR AO and DIO signals to the MID drive analog output, encoder, and inhibit signals. The MID pinouts can be found in the Signal Connections chapter of the NI 7350 user manual (a link is provided below).

To make the physical connections easier to wire up, you can use a pair of SCB-68 terminal blocks and the following cables: