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Potential USB-1608G application



Description of my DAQ application for the “OM-USB-1608G” module:

I would like to have 16, possibly 32, single-ended inputs.

I understand this will require 2 or 4 of these modules, and also the TracerDAQ-Pro software, to be able to use all those input channels. Is this correct?

I need to synchronize the analog samples to an external clock source. It would essentially be a TTL square-wave signal, from DC (system stopped) to about 110KHz.

My understanding is that this module could sample at up to 250KHz if necessary, but I don’t think we’ll ever need to go that fast.

If the external clock signal needs any special voltage levels, I can accommodate accordingly.

As I would likely need to use 2 or 4 of the modules, the CLOCK-OUT from module-1 would need to be connected to the CLOCK-IN of any other modules, so they can all sample at the same time. OR, I could run the same external clock into all the CLOCK-IN terminals.

The analog-voltages I need to monitor are likely to be about 1V P-P, possibly also 0-10V range.

In any case, I can insert level-converting circuitry to safely accommodate the DAQ module.

I haven’t used the TracerDAQ software yet – but I will need to ultimately export the analog samples as a CSV file, ideally with channel on a single line. For example (8 channels):

1.55,1.3,1.5,1.2, 1.25,1.5,1.5,1.2

1.21,1.3,1.5,1.3, 1.25,1.6,1.4,1.5

1.85,1.3,1.5,1.4, 1.25,1.2,1.1,1.9

I do not need timestamps or sample# on each line, but I could easily delete them if necessary.

From what I can tell in the available datasheets, the above seems reasonable and quite feasible. Please advise if I’ve gone wrong somewhere.

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TracerDAQ Pro supports up to 48 channels but only one million samples per channel. Each column in a CSV data file would be a channel and it could have no more than one million rows. The number of channels determines the sample speed. If you're using 16 channels, the high rate is 250k hz divided by 16. You could purchase the USB-1608GX for more speed because it is twice as fast as the USB-1608G. So it would be 500k hz divided by 16. TracerDAQ works with multiple devices but does not have the necessary code to synchronize two USB-1608G devices using the external clock from one to the other. Our DAQami, DASYLab, and LabVIEW support don't either. DASYLab, however, allows the device to be set to use the external clock input to pace the acquisition if you can supply the TTL clock. 

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Unless the Omega website is incorrect, it seems the USB-1608GX model isn't listed for sale (though I can see it's present in some product documentation).

Yes, I would prefer to have the GX model, but I could live with the slower G model if necessary.

Just to clarify one point... does TracerDAQ-pro have the ability to A) use multiple USB devices, and also B) configure all of them to sample using an external TTL clock?

If yes, then I can certainly drive 2 or more of the USB modules from the same external TTL clock source. I don't *have* to physically wire the sampling-signal in a daisy-chain fashion. That specific configuration detail isn't important to this task.

Even if TracerDAQ can't merge the data captured from 2 USB modules into a single CSV file, I can deal with that in post-processing.



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