BNC-2110 Voltage Drop with Multiple Connections

[GiacomoLafontana]

Hello NI Community,

I'm facing a weird issue with our setup. The issue with our equipment when sending an analog signal into port AI3, the signal voltage drops when connected via a T-junction. The problem is not the T-junction itself, but there appears to be significant signal "leak" when both wires are connected to the T-junction which is connected to AI3 on our board. The voltage sent to AI3 could be 5V or it could be 10V, it doesn't matter, but the test panel voltage reads as 1.6V and dropping to 1.4V when both wires are connected. 

I'm wondering if this could be an issue with the board itself, or the BNC cable connections? We also recently upgraded our equipment, and we are now using a Vidrio vDAQ board to generate the analog signal sent to the BNC-2110. Any help/suggestions are appreciated, I am new to this work and trying to learn. (Apologies for the messy setup, cable management hasn't been the priority of this team)

Thanks!

[AnalogKid2DigitalMan]

Is that coax cable connected to the T in your picture fully seated and twisted to the fully engaged position?

Have another T to try? I have come across a faulty one or two before.

-AK2DM

[GiacomoLafontana]

I've tried a few T-junctions to see if that would solve the issue, but that hasn't worked (I'll keep trying just to be sure).

Additionally, something I forgot to mention is that the T-junction has connections from the vDAQ board (which sends a 5V signal), and from the User1 port on the same 2110 device. The voltage only drops when the connection from User1 is connected.

[AnalogKid2DigitalMan]

What pin on the 2110 do you have User1 connected to?

-AK2DM

[santo_13]

If you directly connect signal to BNC-2110 and don't observe the voltage drop, it is clear that the T-Junction and whatever else new connects to the T-junction is the source of problem.

[GiacomoLafontana]

Hello,

The USER1 pin has three connections that go to it: PFI1/P1.1, P0.4, and P0.0. I've attached a diagram photo provide a visual explanation.

I've also narrowed down the problem since yesterday, and now I think the source of the voltage drop comes from the P0.4 -> USER1 pin wire connection. Just from testing today, when P0.4 is disconnected from User1 but all other connections remain in place, the voltage stays steady at 5V. 

I think adding more than 2 wired connections into one spring terminal block is not recommend, but these connections were fine before we upgraded to the new Vidrio vDAQ hardware. I could start with replacing the wires and see if that solves the issue, but if that doesn't work I'm not sure what to try next? Could this also be an issue with the grounding?

[santo_13]

Let's take a step back. Why do you wire two DIO lines into a connection (essentially a short circuit if any one of those is an output). What are you trying to achieve? And where exactly is P0.0 connected to?

USER1 and USER2 are spring terminals to the BNC loopback