BX-04AD-3 in 0-5v is not giving full 15 bit resolution

[friesen]

I am trying to use the BX-04AD-3 with 0-5vdc input.
When it is running with no input connected it shows 4107 on WX0.
If I connect 1C to WX0 nothing changes.
If I connect WX0 to ground then WX0 goes to near 0, about 7.
It is supposed to have a range from 0 - 32767.
It says this in the manual and in the Do-more module configuration.
If i connect a 1.5vdc battery WX0 goes to about 10,000, so it is working.
Can anyone help me with this?
I have tried two different cards with the same results.

[rlp122]

When you have a voltage input that isn't connected, it acts like an antenna and collects any stray RF signals that might be present.  All an antenna is is a wire with no connection on one end.

If you need something that goes to zero with no connection, you need to use 4-20ma.  That's why it exists, because voltage based signals don't do that.

If your issue is that you can't get full range, then you need to look at the impedance of your circuit and what the sender is capable of driving.  If it is drawing too much current, then the signal will never get there.

[friesen]

Thanks for your input, but that doesnt address my problem.
Even when I connect the circuit, it still sits at 4107 on WX0.
It is not picking up stray RF.
All inputs are at 12.5%, ~4107/32767.
I would be ok if the range was 4107 to 16383, but that is not what the documentation and the module configuration say it should be, so I'm trying to get it set up correctly.
The circuit is very simple, 12" of wire reading off a small 0-5vdc output CT.
The issue seems to be in the module, or the configuration of the module.
I dont see anywhere that i need to add something in the circuit to bring it to ground, to get it to go to zero.

[rlp122]

If you aren't using twisted shielded wire, you still could be picking up stray RF.  Voltage is ridiculously easy to induce into wiring. 

Take a look at pages 8-11 to 8-17 of the BRX user manual for some tips.

https://cdn.automationdirect.com/static/manuals/brxuserm/ch8.pdf