BNC-2090A Ground for differential signal output

[Sigi123]

Hi, I need to connect a galvo driver to an analog output from a BNC-2090A. The galvo driver expects a differential signal between -10 and +10 V and requires also a ground reference. I have connected the + signal to the core and the - signal to the jacket of a BNC cable and I am running an additional ground wire next to the BNC cable. I am wondering where I best connect the ground wire to the BNC breakout... Thanks!

[niarena]

Does the galvo driver has a ground pin?

The ground connection will depend of the DAQ device that you are connecting the BNC to, and the kind of grounding that the galvo driver need, if it is just a ground to the chassis, you could use the ground of the device and connect it to the ground of the driver.

please attach some picture or datasheets of your devices to have a better idea of the project. Also you could check the pinout of the DAQ device that you are using and look for the ground pin

[Sigi123]

Thank you for your reply! I have attached the wiring diagram of the galvo as well as the manual. I am using a PXIe 6341 DAQ device with the BNC-2090A breakout. I cannot find any information in the DAQ manual for how to do this. It only says that in the BNC the shield is connected to AO GND.

[niarena]

from the diagram you attached, the grounding they want is to protect the cable from working as an antenna ad receive electromagnetic noise.

On 2.0 Installation and Initial Checkout, pg 7.

"Ground either the heatsink or one of the two #4 screw holes located on the left two corners of the board (see drawing D04244) to chassis ground or the enclosure for best noise rejection. Use a ground strap if necessary to ensure a good connection"

check pg 1-7 from the manual http://www.ni.com/pdf/manuals/372101a.pdf

[Sigi123]

Thank you. Then I think what I will need to do is:

Take a triaxial cable and solder J1.3 to the pin, J1.1 to the inner shield and J1.2 to the outer shield. J1.2 is internally on the driver board connected to ground. On the DAQ side, I use a triaxial to coaxial adapter that leaves the outer shield unconnected.

Please correct me if I'm wrong.

[niarena]

If the DAQ outer shield is not connected, you can use the digital ground of the BNC-2090A

Pg 14 http://www.ni.com/pdf/manuals/372101a.pdf

Digital Ground—Use this setting when the BNC-2090A metal case is not connected to any other ground through a rack mount or connected to the DAQ ground through a shielded cable. Use this setting when using unshielded cables.

For the connection of the pins in the driver I guess it depends on how you plan to use the driver but I am not familiar with that particular driver. This is something I found on the manual:

On the connection of the J1  pin. Pg8. For Analog Differential.

Scanner rotates CW for J1-3 higher than J1-1 [If there is no other ground path to the signal source, J1-2 must be connected to signal source ground.]