Into the thick of things
Enhanced Modbus library implemented in the Java programming language
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I doubt anyone has found this project yet, and if they have, they've noticed things have slowed down a bit.
I'm currently working my way through three very powerful, and very complex, sets of Modbus messages.
The current item on my plate is READ WRITE MULTIPLE REGISTERS. What is so powerful about this message is that it allows an application which is accessing a supporting device to perform a read and an update in a single transaction. What is so complicated is that there is a lot going on with this one message.
The next two items are READ FILE RECORD and WRITE FILE RECORD. These two messages allow applications to access large scale data stored on supporting devices. Imagine a data acquisition system, or process control device, which is able to store long-term data. I don't know of any open source Modbus product which supports these messages, and with slave side support being provided by j2mod, device developers will have the ability to provide these features to their customers.
So please bear with me as I slowly plow my way through the code.
The READ FILE RECORD classes have just been uploaded, which means that WRITE FILE RECORD is the only major message left.
These records have fairly complex structures, but provide incredible value to the Modbus developer.
What devices support these advanced modbus commands?
Many of the missing messages in jamod are common in modern Modbus devices. For example, REPORT SLAVE ID and READ MODBUS ENCAPSULATED INFORMATION are both used to determine which device is at what address.
Other messages, such as the read and write record commands are used by data loggers and devices with larger amounts of storage than registers and bits.
For serial devices, the diagnostic messages are used to determine the health of the device -- this is another complete class of messages which are new to j2mod.