Re: Ada and linux real time

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 19 Mar 2012 09:11:16 -0700 (PDT), slos wrote:

> As I am learning Ada after some procrastination, I thought I could
> implement a simple PLC like control framework that could run on a RT
> Linux context, allowing very simple to quite complex control
> applications.
> 
> The user would benefit the overall structure and components from the
> framework and program his application logic in some Ada procedures.
> Even if only knowing IEC 61131-3 languages, a PLC programmer could
> learn by doing since Ada basics are quite easy to learn.
> One can compare with Structured Text, one of the languages defined in
> IEC 61131-3.
> 
> Although Ada looks to me appealing for control application
> development, I think no one will give a try to this framework if it is
> not available to anybody and GPLed on one hand and performing well on
> the other.

Distributed control applications is what we are using Ada for.

> What do you think about my light sabre ? ;-)

You don't need an RT OS for most PLCs. Even Windows is real time enough to
deliver 5ms cycles.

Of course, it depends on the physical process. The things we control are
very fast (burning processes). This is why our cycles are quite short
0.2-0.1ms. But that is rather an exception. For mechanical systems 1ms
should be enough. And more mass you have to move, longer can be the cycle
and less should you worry about the jitter.

So, if the sabre is not of light, you could just use Windows or normal
Linux.

The superiority of Ada is that what you write is truly portable. Our
engineers test their models right under Windows and only when these work
they actually try VxWorks. The code is exactly same, no modifications
needed. The sensors/actuators and networking communication is decoupled by
a middleware, which is also written in Ada.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de