what happen if we connect two analog output to the same device

[PKIM]

Hi all,

  What happen if I connect two analog output (AO1 and AO2) to the same device but have AO1 and AO2 output exclusively (i.e. either AO1 and AO2 will be outputed at a time not both). The reason why I want to do so is to sending two continuous wave form at different rate at a time. I want to output one set of samples at rate1 to AO1, when it done, I output another set of samples at rate 2 to AO2. My question is if there is any problem if I connect in that way?

[Henrik_Volkers]

It depends....  ( This indicates missing information 😉 )

What type of outputs do you have? (While saying: "either AO1 and AO2 will be outputed at a time not both") 

Can you disconnect the outputs? Are they floating or terminted with a certain impedance or forced to zero?

What type of input do you want to feed? (Impedance? ) which ranges do you have (output) and do you need for the input?

And why not using a single output and do the adding in software?

And what degree of THD do you accept?   (Some AO amplifier will degrade in THD when they source something else than a resistor to GND)

[PKIM]

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@Henrik_Volkers wrote:

It depends....  ( This indicates missing information 😉 )

What type of outputs do you have? (While saying: "either AO1 and AO2 will be outputed at a time not both") 

Can you disconnect the outputs? Are they floating or terminted with a certain impedance or forced to zero?

What type of input do you want to feed? (Impedance? ) which ranges do you have (output) and do you need for the input?

And why not using a single output and do the adding in software?

And what degree of THD do you accept?   (Some AO amplifier will degrade in THD when they source something else than a resistor to GND)

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Thanks for the reply. Honestly, I don't know much about the type of outputs. Both analog channel 1 and analog channel 2 are common grounded and they are connecting to the the external device with BNC so I think both AO1, AO2 and the device are common grounded also. The input impedence of the external device is 50Omega. The input range is from 0 volt to 10 volt (maximum 10volt).

Actually, I don't expect the sum of AO1 and AO2 as the output. I want that while AO1 on going, AO2 doesn't output anything; while AO2 is on going, AO1 doesn't output anything. So only one output will be active at a time.

The reason why I did that is the external device is in a black box, it only has the input terminal. I want to output two different waveforms to that device. Firstly, send out the first waveform, wait for the a button click and then write another waveform. I don't know how to achieve that so I am thinking if it is possible to use AO1 for sending the first waveform and use AO2 to send the second one. I try to send both waveform with the same analog channel but before I send the second waveform, I need to write the samples to the buffer first, which takes time. I expect short time between each waveform.

[RavensFan]

Analog outputs are always sending out something.  They might be sending out 10V.  They might be sending out 0V.  But it is always something.  Even when you are no longer writing data to the output, the last output written will be the voltage output.

You need to learn out to program.  Wire up a single analog output port.  When you want to send one waveform, you write that to the analog output.  When you want to send the other waveform, you output that one to the analog output port.

I would recommend looking at the online LabVIEW tutorials
LabVIEW Introduction Course - Three Hours
LabVIEW Introduction Course - Six Hours

Also look at the example finder for examples on how to use the DAQmx functions.