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Posts from — February 2010

USB Digital to Analog Converters with Timed Outputs

Recently, I had what seemed like a simple task: select a DAC (digital to analog converter).  There are hundreds of models, so it should be easy, especially since most of my requirements were not demanding (1 channel, 12-bit or better, 1KHz output rate, 0-10V, low jitter output, and reasonable cost, hopefully <$500).   Even my low jitter requirement wasn’t demanding; I’d be happy with 100 microseconds of jitter; basically, any unit with a decent FIFO buffer and a hardware timed DAC update should work.

But finding candidates was a lot of work.  Early on, I concentrated on USB DAC models, because they have sufficient speed, are self-powered, tend to be reasonably priced, and don’t need a PCI or PCIe slot.

I’ve used Measurement Computing before, so they were one of my first stops.  It was really hard to find exactly which models have FIFO buffers and hardware paced outputs.  I had to do a lot of searching — and reading the full manuals.

The cheapest Measurement Computing model that met my requirements is the USB-1208HS-2AO, which is overkill ($599, high speed USB 2.0, 2 12-bit analog outputs at 1MHz, DAC has 4K FIFO buffer).  As far as I can tell, nothing cheaper has a FIFO buffer for the DAC.

Data Translation wasn’t much better; I had to dig through the detailed specs PDF to discover that the DT9812-10V meets my requirements, and has a 2K FIFO buffer.  It’s $375; DIN Rail mounting is an extra $60.

The final contestant is the Accesio USB-DA-12-8A, which has a 128K samples buffer.  It’s $525; DIN Rail mounting is an extra $19.

For my application, the Accesio looks the best fit; it more than meets all my requirements, I like the large buffer, andI like the DIN Rail mounting option.

Update Aug 2014:I was look at USB DAQ devices again, and I’m happy to say the situation is much better now.  For example, MCC’s USB-231 for $249 has 2 16-bit DACs that support simultaneous hardware-paced updates at up to 5KHz.  It also features 8 SE (or 4 DE) 16-bit analog input channels with 50KHz max sampling rate, 8 digital I/O, and 1 32-bit counter / timer.

February 11, 2010   No Comments

The SolidWorks World Effect? Alibre’s Lower Prices, VX 50% Sale

SolidWorks World 2010 just finished.  Maybe it’s a coincidence, maybe it’s not, but at the start of SolidWorks World Alibre announced “permanent” lower prices (no guarantees they won’t change prices again, but I suspect they’ll stay the same for a while).  And VX has just about everything 50% off until March 1.

Alibre’s prices now include Alibre Translate (which was $499).  (Alibre pricing info via World CAD Access).

Alibre Product Base Price Annual Maintenance With Maintenance
Design Standard $97 $97 $194
Design Professional $497 $147 $644
Design Expert $997 $197 $1197

VX’s current sale (through March 1, 2010) is VX Innovator for $495, VX Designer for $2000, VX Mold & Die for $3000, VX 3D Machinist for $4000, and VX End To End for $5000.

VX definitely looks more capable than Alibre, but it’s significantly more expensive (including, I’m sure, the annual maintenance fees).  So far, I’ve been able to do some things in VX Innovator I can’t do in Alibre, but Alibre has very few license restrictions.  For example, VX Innovator limits assembly creation to 40 parts maximum (it can import models with more), while Alibre Design Standard does not have any hard limits.  Also, Alibre lets you install Design on up to three computers, which is very nice for those of us with multiple PCs.

I think that if you do anything with 3D solid modeling (not surfacing), then Alibre is definitely worth a look due to its low price, lack of artificial limits, and good import/export options (especially now with Alibre Translate).  If Alibre can improve the ease of use, maybe it can become what SpaceClaim originally claimed to be: MCAD for the rest of us (non-designers), people who need to occasionally work with 3D, but aren’t designing complex parts all day long.

Right now, I’m still sticking with Alibre Design Standard V11 and VX Innovator; if I do a lot of CAD this year, I’ll look at upgrading to Alibre V12.

NOTE: Updated 2/4/10 to reflect Max Freeman’s comment.

February 3, 2010   9 Comments