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Subject: | Modbus R2-10-1 available |
From: | Mark Rivers <[email protected]> |
To: | Mark Rivers <[email protected]>, epics Techtalk <[email protected]> |
Date: | Fri, 15 Sep 2017 20:44:03 +0000 |
Folks, Just after releasing R2-10 this morning I realized there was an important outstanding pull request. I have merged it and done some testing, so I am now releasing 2-10-1. This is the new item from the release notes: - Previously the Modbus/TCP transaction ID was set to 1 on writes and ignored on reads.
Now the Modbus transaction ID is incremented by 1 on each message sent by the driver.
On the reply the driver waits until a message with the correct transaction ID is received, ignoring messages with any other transaction ID.
This is more robust, especially for Modbus/UDP links. Thanks to Eric Norum for this. This change assumes that the Modbus server correctly implements the Modbus/TCP specification which requires it to echo back the transaction ID that it receives. I have tested this on several Modbus servers. If in the future we find
that there are non-compliant Modbus servers then we can add an option to disable the check on the received messages. The home page is here: http://cars.uchicago.edu/software/epics/modbus.html
The release notes are here: http://cars.uchicago.edu/software/epics/modbusReleaseNotes.html
The documentation is here: http://cars.uchicago.edu/software/epics/modbusDoc.html
The repository is on Github: https://github.com/epics-modules/modbus
, Mark |