Is everybody here?

C

Thread Starter

Curt Wuollet

Hi all

I'm testing the new list and just in time! The project was starting to dominate
the Automation List.

I posted some ground rules to begin to get a little more focused on a first pass implementation of a linux PLC. As I explain in that post, If we can herd the cats into one direction for a little while we can maybe get something done. I felt something looking through the posts today. There's something new, the power that drives the Open Source projects. A lot of people are making this real in their own minds and saying Yes! we can do this. I tried to pull together what I seemed to be hearing and defined some things for the short term. I hope we don't lose anyone but we have to have one target for starters.

Reasons on the other post.

License: GPL.

OS: Linux.

Language: C

Architecture: Modular with platform interfaces, eg shared memory pool, sockets,
TCP/IP. HMI and SCADA should connect with sockets so thay can reside on the
same machine or be distributed.

I/O: First pass, serial and Ethernet.

I've heard some really great things like, Most of a PLC in JAVA, A text ladder language started. I've heard some things that are not so good, OPC, COM, Jini and others that I'm not sure can be open and free. The ideas are coming so fast
that just reading them all competes with coding on the project. I hope this list helps with the time shift. I received the rest of the OPTO22 Ethernet I/O rack today and am working on how to set it up without Windows. It needs a BootP
server to assign it an IP address. I should have it running tomorrow. Tonight I am trying to finish the Modbus map structure so I can post it for comment. I want to explain the I/O map and get it discussed and improved and agreed
upon so those who want to can think about coding a logic engine to it. This will take a while yet as I have been short on time and had too many interruptions.

Those who want to code something now per the ground rules, please say so so we can start a development thread.

Regards

Curt Wuollet


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S
Everything you have sketched out sounds like its headed in a good direction, with 2 execptions, one minor, and 1 major.

First the minor one. I'm not thriled with your I/O choices, as someone pointed out lot's of us have millions of dollars of exisitng I/O that
we are very happy with. In our case A/B

The major one is the application programming language. As far as we are concerned, _only_ ladder logic is acceptable. If we wanted something else, we would not be deploying PLC's

Now a suggestion. The HMI part should be able to connect to existing PLC's, such as A?B. I actually think you will find a whole lot of places that are more willing to try something new in the HMI, than are willing to try it at the control layer.

Cheers.

--
Stan Brown [email protected] 843-745-3154
Westvaco
Charleston SC.
--
(c) 1999 Stan Brown. Redistribution via the Microsoft Network is prohibited.

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L
Send me details of Allen-Bradley protocols under Ethernet & I'll happily do some AB/TCP work for you. I have lots of bits & pieces begged and borrowed from various sources. But AB is both disorganized (ie too many DIFFERENT protocols) & very hush-hush on how they really work with Ethernet.

The only exception is for the ControlNet CIP, which only has value if you have ControlNet application layer's already written.

Regards
- Lynn Linse

> -----Original Message-----
> From: Stan Brown [mailto:[email protected]]
>
> First the minor one. I'm not thrilled with your I/O choices, as someone pointed out lot's of us have millions of dollars of existing I/O that we are very happy with. In our case A/B

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Hello,

Stan Brown:
> Everything you have sketched out sounds like its headed in a good direction, with 2 execptions, one minor, and 1 major.
... The major one is the application programing language. As farr as we are concerned, _only_ ladder logic is aceptable. If we wanted something else, we would not be deploying PLC's <

I think this is a misunderstanding more than a disagreement.

If I understood the intent correctly, it was that the linuxPLC would be written in C but programmable in any number of languages - including stepladder and C, two of the usual options.

Stepladder will definitely be an option for those who want it.


> Now a sugestion. The HMI part should be able to connect to existing PLC's, such as A?B. <

I think everybody agrees that the linuxPLC should be able to interwork with
everything in sight :)


Jiri
--
Jiri Baum <[email protected]>
On the Internet, nobody knows if you are a @{[@{[open(0),<0>]}-1]}-line
perl script...

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