Differential mode on 6250

[nyborn]

Hi,

I would like to ask how to calculate the voltage between AI+ and AI- for differential mode.

I need to make sure for my job. Could you pls help me out? Thanks!

I sent an email to your staff in almost a day. She must be busy today and I am in a urgent. That is why I can not wait and send it here.

Here is the information for example below:

50kohm

One one bias resistor connected to negative: 20Kohm

One current source: 3mA

Should I use a current divider to calculate? you should find the equivalent resistor of the bias and the resistor across AI+ and AI-

I need to make sure. If not, could you tell me how to use ohm law to figure?  

Could you pls send it me quickly? Thanks

[Dennis_Knutson]

Wang,

You simply don't get it. Your 50 Kohm resistor is simply too high. If you insist on using 50K, then you would need a second bias resistor from AI+ to gnd. But, 3ma across 50K is 150 volts. With the correct load (i.e. 500 ohms), then you should be able to use the configuration you've got and simply read the DAQ board for channel 0. If you actually do this you should get a reading of about 1.5 volts.

[nyborn]

Hi Dennis:

That means I need to use small resistor between 100ohm to 500ohm without using AI+ and AIGND, right?

So, when the config is like this, you don't have to put any wire from AI+ pin 68 to AIGND pin 67 ( I mean put any single wire) , is the setup correct?

Regards,

John

[nyborn]

Hi Dennis:

How are you? I haven't heard from you. What is happening? Could you please email me back?