BNC to DIO adaptor/connector for BNC boxes?

[tchiahuahua]

I am trying to set up a PXI connection using multifunction I/O board (6115) and a BNC breakoutbox  (BNC-2090 or BNC-2110) to drive some scanning mirrors and photomultiplier tubes.  Regardless of the application, I am installing some software that walks through the setup of the National Instrument part and in one section it mentioned, "Connect the DIO0 output to the PFI0/TRIG1 BNC using the appropriate adaptors".  What I am wondering is what are the appropriate adaptors?  Is there something that NI makes that is intended for this application?  The DIOO output is a spring terminal (intended for one wire) and the PFI0/TRIG1 is a BNC cable.  What I have done is taken a BNC cable and connected one end to the PFI0/TRIG1 BNC and cut off the other end so the center signal wire goes into the DIO0.  Do I need to do something with the ground part of the BNC adaptor that I have made (eg. ground it) ?

[Albert.Geven]

It looks that both connectors are on the same brakout box so they already share ground.

Otherwise you had to make sure that somewhere the reference levels match!
It is by default impossible to measure volts with only one wire. The only volts to be measured is the difference between two voltages.