Standards & P-Code

W

Thread Starter

Willy Smith

I have been monitoring this list for a while, but this is my first post. Forgive me if I have not gotten and read *all* the mail; this list is very
active.

Reading some of the posts about different standards, variable types, etc., makes me think that the LinuxPLC development could be accelerated by adopting the 1131-3 standard as a first step. All the different types of
variables, functions, and other details have been well specified. This of course doesn't help the HMI spec, but it would save a lot of time, and
guarantees that the *specification* is well thought-out and executed.

The next suggestion is that IL (instruction list) be used for the P-Code. IL is a powerful low-level language, and it is extensible through the use of functions or function blocks. Thus, anything written in ladder, function block, or structured text could be translated to IL without a lot of trouble. There are special constructs and variables so that IL can make an efficient SFC engine, too.

This also would facilitate one other future development that I have not seen addressed: eventually, control will be pushed out to individual distributed nodes, so that some of the logic will be performed at the PC, but some will be performed locally at the I/O point. Adopting a
"lower-level" language for the P-Code would allow this to happen without as much difficulty (as say, Java).

If someone else has already written about this, apologies in advance.

Regards,


Willy Smith
Numatico, S. A.
Apartado 676-4005
San Antonio de Belén
Costa Rica
Tel +506.293.9943
Fax +1.413.332.0065
[email protected]
www.numatico.com



_______________________________________________
LinuxPLC mailing list
[email protected]
http://linuxplc.org/mailman/listinfo/linuxplc
 
J

Jan Krabbenbos

Hello All,

Willy Smith wrote:
> Reading some of the posts about different standards, variable types, etc.,
> makes me think that the LinuxPLC development could be accelerated by
> adopting the 1131-3 standard as a first step. All the different types of
> variables, functions, and other details have been well specified. This of
> course doesn't help the HMI spec, but it would save a lot of time, and
> guarantees that the *specification* is well thought-out and executed.

I think this is a good idea. What I've seen happening that a lot of PLC vendors adopted this standard one way or another. (For AB specialist: AB initiated the talks about a standard for PLC languages. This resulted in the 1131 standards) The acceptation in the world of control may be
quicker and easier.

> The next suggestion is that IL (instruction list) be used for the P-Code.
> IL is a powerful low-level language, and it is extensible through the use
> of functions or function blocks. Thus, anything written in ladder, function
> block, or structured text could be translated to IL without a lot of
> trouble. There are special constructs and variables so that IL can make an
> efficient SFC engine, too.

I agree on this. From IL it is even possible to generate code for different real-life PLCs.

> This also would facilitate one other future development that I have not
> seen addressed: eventually, control will be pushed out to individual
> distributed nodes, so that some of the logic will be performed at the PC,
> but some will be performed locally at the I/O point. Adopting a
> "lower-level" language for the P-Code would allow this to happen without as
> much difficulty (as say, Java).

As far as I remember the 1131-3 standard, it also supports programming for multiple distributed nodes/PLCs. The Java Run-Time environment is a
virtual machine, just like the PLC-engine would be under Linux (or any other OS).

--
Greetings,
Jan



/\ Jan Krabbenbos
e-mail: [email protected]
\/ www : http://www.krabbenbos.com
_______________________________________________
LinuxPLC mailing list
[email protected]
http://linuxplc.org/mailman/listinfo/linuxplc
 
S

Scott Cornwall

> As far as I remember the 1131-3 standard, it also supports programming
> for multiple distributed nodes/PLCs. The Java Run-Time
> environment is a
> virtual machine, just like the PLC-engine would be under Linux (or any
> other OS).

Yes, this thread is dancing around the concepts of configurations, resources and programs as presented in the IEC61131-3 standard.

BTW, 1131 is online at
ftp://ftp.cle.ab.com/stds/iec/sc65bwg7tf3/html/news.htm#1131-3

Scott Cornwall
www.psc.fp.co.nz

_______________________________________________
LinuxPLC mailing list
[email protected]
http://linuxplc.org/mailman/listinfo/linuxplc
 
Top