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A/D and D/A Boards for Linux?
Quadropleen+ asks: "I work in a lab where we do real time control of industrial hardware. To this point, we've been using several old A/D and D/A boards to control these processes under DOS, due to the anti-real time properties of Windows. Well, our cards are beginning to fail, and we're looking for replacements. I've been trying to get my advisor to move to Linux, and I see this as a great opportunity to leverage a better OS onto our machines. Does anyone have suggestions/experience with using A/D & D/A boards with Linux? What are the best and worst ones out there?"
and I post first!
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Hello me...Meet the real me.
And my misfits way of life.
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Hindsight is always 20-20,
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Feeling paranoid
True enemy or false friend?
Anxiety's attacking me
And my air is getting thin
Feeling claustrophobic,
Like the walls are closing in.
Blood stains on my hands and
I don't know where I've been
Once you committed me
Now you've acquitted me
Claiming validity
For your stupidity
I'm chomping at the bit
I'm sharpening the axe
Here I come again.
Sweating bullets
2 years ago National Instruments were starting to support Linux, i don't know about drivers though.
Interesting field and Linux is perfect for this..
A quick glance through their site www.axiomtek.com, I came across a 16 channel board that supports "Red Hat Linux kernel version 2.2.X - AX509SP.
Might want to give these guys a look...
Jeremy
"Opinions are like assholes; everyone's got one..."
In my work as a Test Engineer, I've used boards from Keithley-Metrabyte, Measurement Computing (Formerly ComputerBoards), and National Instruments. All work well with linux, providing you find the right drivers.
One good site for drivers is the Linux Lab Project. There are links to drivers for many different boards.
Another good project is the Comedi project, which maintains drivers for quite a few cards, and supports the use of RTLinux, RTAI, and card access from kernel modules.
My current favorite is the National Instruments E series boards. The drivers in the Comedi project are quite good, and the cards have an excellent set of features.
I'm using boards from Elk in my home automation project... They are based in Charlotte and have some good kit. I'm using two digital IO boards and one analogue all on the same serial port.. with perl code to access the data. They have lots of other very cool stuff too though.
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. -HLM
Since you may want faster (realtime) response time for your application, you may consider using a PLC (www.automationdirect.com, www.siemens.com, www.modicon.com, www.ab.com) and just controlling set points with the computer. There are many many options available in this area, and a PLC is WAY reliable than a PC for critical control functions. Contact me through eMail if you'd like more information.
LOAD "SIG",8,1
LOADING...
READY.
RUN
The suggestion that you look at PLC's is a good one, depending on what you mean by "Real Time". I have implemented many Intel/DOS-based solutions precisely because PLC's are very rarely anywhere near real-time. TI, for instance, has one of the fastest PLC's out, but the conversion times on their A-D cards is typically 250ms+. Doesn't do a whole lot of good to be able to read a port a jillion times/sec if the data there is old news. Makes for real smooth averaging, though!