Thermo Scientific Oretronic III, Operating & Service Manual

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Appendix A
Thermo Fisher Scientific A- 1
REC 4105 Rev L
Appendix A - TMD Modbus Interface
This Appendix provides information about the Modbus protocol
implemented for communications between the ORETRONIC III Tramp
Metal Detector (TMD) and an intelligent host or PLC. It deals only with
the protocol as used for this particular interface.
If you need detailed information about all aspects of Modbus protocol,
refer to Modicon‚ Document Number PI-MBUS-300, Revision J.
The TMD Modbus interface protocol is a subset of the Modicon Modbus
protocol. The physical layer uses an asynchronous serial bus topology
with an RS-485 physical data medium. Transferred data is 8-bit binary
using RTU framing and 16-bit CRC error checking.
Control is restricted to a single master/multiple slave configuration. The
host or PLC must act as a Modbus master device. Baud rates supported
are: 1200, 2400, 4800, 9600, 19200. The default is 9600 bps.
The TMD provides normal Modbus responses only for the functions
listed below; all other functions and diagnostic requests will return
Exception 01 (Illegal Function).
• Function 03 - Read Holding Registers
• Function 06 - Preset Single Register
• Function 16 - Preset Multiple Registers
Holding register reads (Function 03) are restricted to transferring 1 to 16
registers at a time, starting with the specified holding register address.
Any other form of holding register address will return Exception 02
(Illegal Data Address). This is a sub-set of normal Modbus slave
responses.
Holding register writes (Function 16) are restricted to transferring 1 to
16 registers at a time, starting with the specified holding register address.
Any other form of holding register address will return Exception 02
Overview of TMD
Communications
Modbus
Message
Types
Supported by
the TMD