Application Data Unit Definition; Slave Address; Mbap Header - Thermo Scientific Omni FTIR Multi Gas CEMS Instruction Manual

Modbus Protocol
Serial Communication Parameters
Communication
Parameters
Communication
Parameters
Application Data
Unit Definition

Slave Address

MBAP Header

B-2 Omni FTIR Multi Gas CEMS Instruction Manual
Serial
The Modbus/RTU protocol is supported using the ImaccModbus server.
The following are the communication parameters that are used to configure
the serial port of the system to support Modbus RTU protocol.
Number of Data bits : 5, 6, 7 or 8 (8 is default)
Number of Stop bits : 1, 1.5 or 2 (1 is default)
Parity
Data rate
Flow Control
Device address
In addition, the poll delay (10 mS) and response delay (0 mS) are user-
programmable.
TCP
The Modbus/TCP protocol is supported using the ImaccModbusTCP
server. The register definition is the same as for the serial interface.
TCP connection port for Modbus
Here are the Modbus ADU (Application Data Unit) formats over serial
and TCP/IP:
Serial:
TCP/IP: MBAP Header Function Code
The Modbus slave address is a single byte in length. This value can be
between 1 and 255 decimal (i.e. 0x01 hex to 0xFF hex). The default value
is 70.
In Modbus over TCP/IP, a Modbus Application Protocol Header (MBAP)
is used to identify the message. This header consists of the following
components:
: Even, Mark, None, Odd, Space (None is default)
: 110 to 115200 Baud (9600 is default)
: None, Xon/Xoff, Cts Rts, Cts Dtr (None is
default)
: 1 to 255 (70 is default)
Slave Address Function Code
: 502 (user configurable)
Data Error Check
Data
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