Modbus/TCP Object Messaging


Thread Starter

Lynn Linse

For anyone using Modbus/TCP on a product, now includes a "MODBUS/TCP Object Messaging Protocol Extensions" which is designed to support data objects much like DeviceNet or Foundation Fieldbus does. The full spec is at

In a nutshell, they provide a new function (decimal 91) which indicates an object request follows. An object consists of some flags, Object Class Id, Instance Id, Service Code (like get attribute etc) and data based on the service code.

Technically it was created to allow SemaTech objects to be managed in Modbus PLC. It would be interesting to see if anyone has an application for this in new work.


Lynn August Linse, Senior Product Application Engineer
15353 Barranca Parkway, Lantronix Inc, Irvine CA 92618
[email protected]
Tel: (949)450-7272 Fax: (949)453-7132