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Adding an external multiplexer to the analog output

I have a DAQ NI USB-6251 and it only has two analog outputs. In the system I am working on, I use one of the analog outputs for synchronization and the other one for connecting a transmitter. The issue now is that I need to add up to 6 transmitters, so I think I would need a multiplexer connected to the analog output.


I have found this solution:



But I would like to know if there is any inexpensive and integrated electronics from NI, SCXI or any other company that I could connect to the DAQ.


Thanks in advance

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Message 1 of 5

Hi Lady Evellin,


first of all, SCXI means Signal Conditioning eXtensions for Instrumentation, so it is not a device designed to multiplex signals, however it works in multiplexed or parallel mode. This device was designed to "arrange" signals before being acquired with the DAQ board. Here you can see a brief tutorial of signal conditioning:




In case you use a SCXI to multiplex your analog signals, you would have two multiplexers: SCXI module MUX and DAQ board MUX. Too much. You can have a peek into the architecture in the following link:




As you can imagine, this is a very unuseful solution for you and really expensive. The best way for you (I recommend it) is to use an Analog Output board instead of an M Series USB board (6251). This board has multiple analog outputs. You can see it in the following link:




You can have a glance into the rest of them (left column) apart from PCI-6713. You can contact NI for further information. Si eres español/a como creo, puedes llamar al 91 640 00 85. Espero que esta información te resulte de utilidad.


Un saludo.




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Message 2 of 5

Hi, Jesus,


Thanks a lot for the information provided.


I've been checking the possibilities you suggest and the Analog Output Board seems reasonable. But the problem is that I am working on an ultrasound system and I need at least 7 analog inputs for the receivers (which have been already conditioned). So checking the specifications of the board, I have seen that it does not have any analog inputs.


The part of the project I am working on will be finished with the M Series USB 6251, because for the trials I am just using one transmitter, but for the Further Research section, I need to add two topics:


1- Possibilities for increasing the number of transmitters (increasing therefore the analog outputs) to the hardware I already have.

2- Possibilities for substituting the NI DAQ with some other electronics, cheaper for the final solution (such a envelope detector plus comparators, etc..)


Sí, soy española, pero he escrito en inglés, ya que así todo el mundo podrá entenderlo. Muchas gracias de nuevo por la información.



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Message 3 of 5

If you're looking for a USB solution, I'd recommend looking at our cDAQ chassis, which is a modular chassis that you can plug whatever you want into.  We offer both a 4 slot and an 8 slot chasssis (you'd only need a 4 slot and would only be using 3 slots with 8 analog in and 8 analog out).  I'll defer specifics of this configuration to Jesus, but in short you'll need:

One 9174 (4 slots) or One 9178 (8 slots)

Two  9263 modules (4 Analog outputs each, 8 total)

One 9215 or One 9201 or One 9205






-John Sullivan
Problem Solver
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Message 4 of 5
Note that while we can put switches in an SCXI chassis, this probably isn't the best solution for your application.  See my above post for a great USB solution.
-John Sullivan
Problem Solver
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Message 5 of 5