A customer has asked that we find a way to allow their Unix/Linux based computers to have access to a SLC5/05 data table.

I am aware of Ron Gages ABEL project, and that might be an option, but I do not have the Linux/Unix skills to know if thats a real option of not.

Our customer is very serious about doing this so if I suggest an approach I would like it to actually work, so i am inclined towards some kind of commercially available product where the owner has some vested interest in maintaining it.

(This is not a jab at OSS stuf, just legit concern from having been burned in the past using "free" things).

OTOH - I am not aware of any other product that might do what they want.

Any ideas?

 

One of the real issues with Linux in Control is the fragmentation. Now, since it's all open-source, you can always code a connector, but you need C for that. (Hopefully, the field will consolidate, reducing the fragmentation; but that's still on the to-do list rather than reality.)

ABEL can be used directly from a C program. It should also be usable from MatPLC, but I don't think anybody's ever used them together, so there's bound to be at least one bug. There's probably other projects that interoperate with ABEL, but I haven't been keeping up...

In all cases, being comfortable with a little C programming will help a lot, even if it's just to help pose intelligent questions to the developers. You may not end up needing any C, if everything goes well; but when does ever everything go well?

So:

- where does your customer need the data to end up? Screen, database, webpage? Somewhere else? What program is on the receiving end?

- are you (or do you have someone who is) OK with a little C programming?

Jiri
--
Jiri Baum <[email protected]> http://www.csse.monash.edu.au/~jirib
MAT LinuxPLC project --- http://mat.sf.net --- Machine Automation Tools

 

You might ask Ron, I believe he's lurking about here someplace. We don't have any AB "ethernet" around or I'd take a look for you.

Regards

cww

 

I can't offer any advice about specific products, but I can offer some background information that may be helpful.

As a first point, you have described the customer's systems as "Unix/Linux based". You will want to narrow down just exactly what you are dealing with in terms of operating system version, hardware, and what it is being used for. Unix-like operating systems cover a lot of ground. It makes a difference whether you are talking about a super-computer or an Apple MacIntosh.

As a bit of a clarification, on the "Unix-like" question, "UNIX" is a trademark of a computer industry group that certifies whether a particular operating system version meets the official "UNIX" standards. This is similar to the various fieldbus certifications we see in our own industry. For example, when Apple stopped paying their certification fees, "OS-X" stopped being being officially a type of "UNIX" and simply became "Unix-like". Similarly, nobody has bothered paying to have Linux certified, so it can't use the "UNIX" trademark either and is simply "Unix-like". Some people will use the term "Unix" (note the capitailisation versus "UNIX") as a generic term.

You said: "I am inclined towards some kind of commercially available product where the owner has some vested interest in maintaining it."

If this is truly the case, then you should be looking towards something from a large company with a large support group. Simply handing over some money to someone doesn't guaranty any security for you. There was a recent message on this list from someone who was looking for support for a proprietary commercial driver (for Windows) he bought. The company he bought it from turned out to be a one man band who had left the country and stopped answering e-mails.

Companies go bankrupt all the time, as well as being taken over by other companies who then terminate some of the product lines. If you are looking for security, then having a copy of the source code (and the right to change it) is about as secure as you are ever going to get. If the original author disappears, then at least there is the possibility that someone else will be able to make changes for you.

Siemens has an "IT Integration" group which deals with integrating Siemens hardware to Unix/Linux systems for large scale enterprise systems. AB may have an equivalent group. If so, you may need to contact them directly, as they may not operate through their regular distributor network.

Finally, you may try contacting Ron Gage. It is possible that he would be happy to be a subcontractor for this part of the project. ABEL may be open source, but I am sure he has no objections to making money from it.

 

I have done some C programming but its been a long time. We are not responsible for what the end user is doing, I don't even know what it is he plans to do. that's his issue, not mine. My issue is to get something that will give him the warm fuzzies that his 'nix programmers can work with.

Bob Peterson

 

On May 16, 2004, Michael Griffin wrote:
> As a first point, you have described the customer's systems as "Unix/Linux
based". You will want to narrow down just exactly what you are dealing with in
terms of operating system version, hardware, and what it is being used for.
Unix-like operating systems cover a lot of ground. It makes a difference whether
you are talking about a super-computer or an Apple MacIntosh. <

As I understand it, they can use either Linux or some form of Unix running on an HP minicomputer of some sort. They are eventually converting their whole system to linux so I suspect they would prefer something in the Linux world, but will accept a unix solution as long as it will run on their computers.

<clip>
> You said: "I am inclined towards some kind of commercially available product
where the owner has some vested interest in maintaining it."
>
> If this is truly the case, then you should be looking towards something from
a large company with a large support group. Simply handing over some money to
someone doesn't guaranty any security for you. There was a recent message on
this list from someone who was looking for support for a proprietary commercial
driver (for Windows) he bought. The company he bought it from turned out to
be a one man band who had left the country and stopped answering e-mails.
>
> Companies go bankrupt all the time, as well as being taken over by other
companies who then terminate some of the product lines. If you are looking for
security, then having a copy of the source code (and the right to change it) is
about as secure as you are ever going to get. If the original author
disappears, then at least there is the possibility that someone else will be able to
make changes for you. <

True, but the warm fuzzies is an important sales tool, and giving it to them may well increase the chances of a sale.

> Finally, you may try contacting Ron Gage. It is possible that he would be
happy to be a subcontractor for this part of the project. ABEL may be open
source, but I am sure he has no objections to making money from it. <

I have emailed him and at present our plan is to suggest they use ABEL and contact Ron for technical support if/as needed. My guess is they won't need much help, they have a large network and many hundreds (perhaps thousands) of
such teststands runnin gin their plants, so my guess is they would have the expertise to integrate ABEL into their system.

Bob Peterson

 

Integrating hundreds of anything reliably pretty much requires Linux or UNIX or admins on skates. Sounds like my kind of place.

Regards

cww

 

Well, you could always use ASC blocks on the 5/05 to read/write <XML> or any other user-defined protocol on the RS-232/CH0, which connected to a simple low-cost RS-232-to-Ethernet "Device-Server" to encapsulate this into TCP/IP. Sounds silly, but the 5/05 has some nice string functions and can manage String data files. It just depends on how much data your customer wants. Then you could run Java or Python or any Linux tool you want on the host end of the link.

- LynnL

 

This is an upgrade to an existing system that uses an SLC BASIC module to do just about what you are suggesting. They want Ethernet. Give the customer what he wants I always say.

 

In that case, ABEL should be perfect - 'nix programmers almost certainly means the C language, and ABEL is a C library.

Jiri
--
Jiri Baum <[email protected]> http://www.csse.monash.edu.au/~jirib
MAT LinuxPLC project --- http://mat.sf.net --- Machine Automation Tools