NI DAQ USB 6001

[tdpd78]

HI,

I am using the DAQ USB 6001 and I already have an analog input with its own ground terminal connected to AI0 and AI GND. Can i connect another input signal to the AI2 and its ground? When i tried to do so, the voltage is dropping drastically. 

Any suggestions please? 

Thanks.

[santo_13]

Where does the analog signals come from? how exactly are you connecting - a schematic will help.

[tdpd78]

The equipment is an old type FFP controller. This equipment doesnt have any GPIB/LAN/USB facility. So, we hardwired one of its front panel control (lock/Unlock button) to the DAQ AI 1 input. So, instead of pressing on the front panel, we will be sending a signal through DAQ from PC. The same equipment has an output terminal that displays the Lock voltage. This output from the equipment (o/p voltage) we want to monitor using the same DAQ by connecting to different AI pins. 

The moment i connect this O/P voltage ground terminal to DAQ's AI2 GND, there is a voltage drop. 

So was wondering if these two ground signals might be different and DAQ can not be used with multiple dfrnt gnd terminals?

Any ideas?

Thanks.

[santo_13]

Something is wrong. you cannot connect a Analog Input to another Input (lock/unlock button). It should have been a DO channel wired to your button.