Why the maximum voltage is 5V in unipolar mode with PCI-6024E?

[antsfan]

Dear experter:
Appreciate for your answer.
I try to use the PCI-5024E card to get analog input (0-10V) with my own program written in Visual C++ 6.0. At first I use "AI_Cinfigure(1,0,0,10,1,0)" to set the input mode of channel 0 as DIFF and unipolar mode. The IO connector is "V+ connect to ACH0(68), V- connnect to ACH8(34), directly connect ACH8(34) with AIGND(67)". When the input voltage is more than 5v, I only can get the 5V from AI_Vread or "AI_Read and AI_Vscale" and the reading interger is 2047 that should be more than 2047 for unipolar mode(the reading interger should be in 0-4095). If the input volage is less than 5V, the value get from DAQ card is right. I also tried RSE and NRSE mode with th
eir specific IO connector, I got the same result, which can't be greater than 5V. But I try the Measurement & Automation, I can get the result greater than 5V correct. The question looks like that I can not change the DAQ card inputmode and polarity by my own program( the default polarity of DAQ card is bipolar). What is wrong with my program? Could give me any suggestion to change the polarity of the DAQ card? Appreciate for your help very much.

Antsfan

[Doug_Norman]

Hello,

I'm not familiar with the C++ NI-DAQ interface, but I'd be willing to bet that your problem is you need to set the gain to 1/2.

Regards,

Doug

[antsfan]

Hi, Doug:
Appreciate for your help. I already solved the problem. If I set the gain to 1/2, the value is right, and the measurement range looks like -10V~10V. Also, I got some information, the PCI-6024E card can't be configured as unipolar mode.
Thanks you again, it is a real good suggestion.

Antsfan