CompactLogix to AS/400 communications?

I'm swimming in unknown waters and need some help. I mostly program in C, Java, PHP, and RPGIV. I've been asked to get my AS/400 to talk with a PLC. I don't even know where to start.

Here's what I want to happen. A barcode is scanned from the PLC. The PLC sends the barcode info to the AS/400 which replies with the necessary settings for a machine based on the barcode.

Can the PLC call a program on my box through ftp or how do I do this? Another option I've thought of is have a program create a file, and transfer the file to the PLC with the necessary settings for the machine.

By AS/400 do you mean one of IBMs servers?

What type of connection exists between the PLC and the server, RS-232, Ethernet?

Yes, I mean an IBM iSeries server. As far as the connection it's ethernet.

Well, if it's Ethernet you are somewhat limited with the Logix processor as it will only support their protocol, Ethernet/IP. So that being the case you must either implement their protocol on your system or get some hardware that allows you to implement a protocol of your own on the PLC. As far as the former, and depending on the OS you are using, you may want to check out http://www.rongage.org/. He may have some libraries that can communicate with a CompactLogix over Ethernet. There are of course commercial libraries available also.

If you feel the latter would be a better approach, check out Prosoft Technogology's MVI69-ADMNET module. It's a 3rd party communications module that goes in the chassis and has two serial ports and an Ethernet port. It runs a little industrialized DOS OS, and comes with an API to access the backplane, serial ports, and network services. You write your own programs in C, so you might find this familiar. I've used versions of this for other processor families and love 'em. The down side to this approach is you have to invent and implement a protocol on both ends.

One final alternate requires you to get a RS-232 connection to the processor, which can be with a serial device server with can remotely locate a serial port over an IP network. You only need to implement AB's DF1 protocol in your server as the PLC. There are also many free and commercial libraries available for this. In fact one of my little hobbies is an open source DF1 library:

http://sourceforge.net/projects/libpccc/

FYI my library is designed in a client/server model so your server doesn't need direct a RS-232 connection to the PLC. For example you can use a local host with a serial port that will provide a DF1 service over the network and use the client library in the AS/400.

Those are a few ideas off the top of my head....

Another possible route is to use RS Linx to connect to the processor and to the Server via OPC. OPC gets you ODBC compliant and as such you could use Excel or SQL as a connector DB and pass everything through there.

A more powerful route would be RSSQL which gives direct connection between PLC and a DB.

This all over Ethernet IP, no serial connection required!

I've done both so if you need more info feel free to ask.

I would look at www.igearonline.com

They have experience in setting up their transaction server in combination with the AS400 OS. They helped on of our customers to get connected to DB2 on a OS390 IBM mainframe. I do not know if Rockwell has stated their intention of future viability of RSSQL. I would ask some very careful questions before setting up a critial system that relies on RSSQL.

Darren