Thermo Scientific Omni FTIR Multi Gas CEMS, Instruction Manual

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Thermo Fisher Scientific Omni FTIR Multi Gas CEMS Instruction Manual B-1
Appendix B
Modbus Protocol
This appendix provides a description of the Modbus Protocol Interface and
is supported both over RS-232 (RTU protocol) as well as TCP/IP over
Ethernet (TCP).
The Modbus commands that are implemented are explained in detail in
this document. The Modbus protocol support for the Omni FTIR Multi
Gas CEMS enables the user to perform the functions of reading the various
concentrations and other measurement values and status as well as trigger
the various system sampling modes. The
ImaccModbus server software
allows the data acquisition computer to serve as a slave on a Modbus
network. It transmits data archived in the ASCII concentration data files to
the Modbus master in response to an
F03: Read Holding Register command.
ImaccModbus uses two Modbus registers to transmit concentration and
measurement data in floating point format. The TCP version also has the
ability to accept an
F06: Write Single Register command.
For details of the Omni FTIR Multi Gas CEMS Modbus Protocol
specification, see the following topics:
●
“ Serial Communication Parameters ” on page B-2
●
“ TCP Communication Parameters ” on page B-2
●
“ Application Data Unit Definition ” on page B-2
●
“ Function Codes ” on page B-3
●
“ Modbus Parameters Supported ” on page B-5
Additional information on the Modbus protocol can be obtained at
http://www.modbus.org . References are from Modbus Application
Protocol Specification V1.1a Modbus-IDA June 4, 2004.