Support for Allen Bradley
to communicate with Allen Bradley PLC's
they're a major player in the world of automation - communicating with them gives you that much more credibility.
Undoubtedly you are correct. However, there is a great deal of equipment around, and only so many programming resources to support it all. Also, proper protocol implementation often requires access to hardware to test against, making it sometimes financially prohibitive (that is, as long as we plan to continue to provide Mango at its current price point, which we do).
We therefore have to prioritize what equipment we intent to support. There are two main factors that affect prioritization:
- if we receive a lot of user requests
- if users offer to fund development
Please do not interpret this post as stomping on anyone's wishlist. Indeed, i make this post to assure you that your items are being considered, and to explain why some may be realized more quickly than others.
how long would you need to have access to hardware to do a good job of testing a protocol?
Depends upon the protocol, but testing typically takes on the order of days. The implementation of the protocol is the bigger piece, usually taking days, but in some cases (like BACnet) taking weeks. Often protocols are proprietary, and so the problem is getting the specification. Even "open" protocols like BACnet cost money though.
In short, the implementation of a data source requires three things:
- the protocol specification
- hardware to test against
- time :)
wow, you're quick with the replies.
The AB protocol is widely used... I'm under the impression that I can get it.
If I sent you the protocol spec and a PLC for a couple weeks, is this something you would implement?
If you forward the protocol, i can give you an idea of the effort involved. We can go from there.
There is an open source communication library for AB PLCs at http://www.tuxplc.net/index.php?page=tuxeip
That library has a couple of issues. It is written in C/C++ and so does not easily work with Java, and would almost certainly restrict Mango's cross-platform ability. Second, it is released under the GPL license, which means it could only be included in the Open Mango product, not the commercial version.