High channel count: multiple cheap DAQs vs. single expensive DAQ?

[LVBrendan]

I need 4  analog outputs but the resolution isn't critical, the cheap USB-6008 will suffice. Is there any reason to buy a more expensive DAQ (like the USB-6351) with many channels vs. multiple cheap 6008's? 

Seems like bad practice, but I can't think why. . . 

[johnsold]

The more expensive devices may have hardware timed outputs.  They may also have options for synchronizing the outputs.  The 6008 has neither of those features.  If you do not need the features, you may not need to pay more.

The USB-6343 has 4 AO channels in one device.  There are PCI and PXI cards with 8-32 channels of AO.

Lynn

[SnowMule · Accepted solution]

I've done systems both ways.

Pros to more expensive DAQ: Single connection, single device to set up in MAX, and like johnsold said, you usually get better resolution, accuracy, and timing out of it.  Cons, obviously, cost... but also physical size. 

With multiple smaller DAQs, in benchtop production equipment this means either multiple USB ports on the side, or the use of a USB hub.  More ports means more cables, and something else for manufacturing to screw with.  USB hubs can cause problems on certain computers, and are generally the first thing I yank out when troubleshooting.

Upside, you're saving lots of $ buying two or three 6008's at 150/ea vs. a bigger 6343 at 1500/ea. 

If you do use a USB hub, get something like this Startech unit.  They're worth the price difference from the el-cheapo consumer-grade hubs.  Nice thing about that one is if you've got decent 12v power in your system, you can power the hub right off that and use a USB port as a 500mA/5V supply for relays/LEDs/etc driven from your DAQ(s). 

[LVBrendan]

thanks all for your input!