Reference for Modbus Implementation in Java
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I am looking for feedback on various Modbus implementation in Java. Can anyone share their experience with FieldTalk Modbus library, jamod, modbus4j, and modbuspal? What are the pros and cons with each library? Is there any other third party library I can look into?
I have used jamod, it works quite fine with some modbus simulators, but today I tried with the PLC I would like to communicate with (T2550 from Eurotherm) and it did not work(java.net.SocketTimeoutException:ReadTimeout).
I coud communicate well with a supervision screen from Movicon.
There are a large number of bugs in jamod, especially with message timeouts. The library seems to make very naive assumptions about the underlying drivers and I had a lot of difficulty. So, I forked jamod and came out with j2mod. Not only does it work better, it's also being supported ;)
Hi Julie:
I have checked the Bug Tracker and I did not find a single bug that was reported by you.
Then I have checked the Feature Requests and I did not find a single request that was filed by you.
There was also not a single Patch filed by you, nor was there any Support Request.
(Note: filtered for jfhaugh)
I worked on this back in 2000 and it started on an embedded system, without any support for the serial protocols. Actually this support has been added by John, whom I am thankful for supporting his implementation ever since as well as he could.
All of our work has been available to the public free of charge and under a license liberal enough to allow anybody to use it for their own efforts (even commercially without retribution).
I have very often supported people that requested help from me directly and I have gone through some really difficult times, so that I might as well have sometimes left behind one or the other request (shame on me, but a roof above the head and some food on the table for my family might have been more important).
Jamod might not be a product by itself, but for open source jamod is actually pretty well documented:
http://dieter.wimpi.net/2007/03/os-project-feature-jamod.html
http://dieter.wimpi.net/2010/04/jamod-some-faqs.html
You would have been welcome to actually take a stake in jamod and help to make it better. But it's great that you took our work and derived something more useful from it. Many more have done this before you (and I have and will link those efforts from the site when I do updates again).
If you think we are doing something wrong, please file a report and maybe even a possible fix, instead of pointing out everywhere that you are doing everything better and that jamod sucks.
I am sorry if you feel that we did a bad job or that we didn't take your contributions (whereever they may have gone instead of into the trackers) into account.
But please, for the sake of tolerance and my believe in humankind, stop bashing and start to be more constructive either here or over at your own project.
Thanks and best regards,
Dieter