What's the range of the analogy output?

[dragondriver]

Hi all,

  I have been using labview and traditional DAQ for long time, in which I never pay attention to the output range (minval and maxval) in analog IO. But I just switch to CVI and I have to learn how to use the DAQmx functions. For analog output, I use the function DAQmxCreateAOVoltageChan to create the taskHandle. I am controlling one analog output channel with voltage 0 to 3V, and another channel with voltage -1 to 5V, so I set the min and maxval to 0 and 3; -1 to 5

DAQmxCreateAOVoltageChan(taskHandle1, channelname1, "", 0, 3, DAQmx_Val_Volts, "")

DAQmxCreateAOVoltageChan(taskHandle2, channelname2, "", -1, 5, DAQmx_Val_Volts, "")

But running this program will pop up an error to tell that the specified range is not right. So what's the range really for? What value should I use?

[margasan]

Hello Dragonriver

As the help files explains: "

Input limits are the maximum and minimum values you expect to measure, after any scaling, including custom scaling. Input limits are sometimes confused with device range. Device range refers only to the input range of a particular device. For instance, the device range for a DAQ device might be 0 to 10 V, but that device might be used with a temperature sensor that outputs 100 mV for every 1 °C. The input limits in that case could be 0 to 100, with 10 V corresponding to 100 °C.

Input limits in a smaller range can improve the precision of your measurement. If, in the previous example, you knew that the temperature would never be higher than 50 °C, you could choose a minimum value of 0 and a maximum value of 50. The device can then detect smaller differences in temperature because it is digitizing a voltage between 0 and 5 V, rather than 0 and 10 V."

What DAQ card are you using? have you tried the shipping example and modify the range using the example code?

Regards

Mart G