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PBD-51041059
SITRANS LG260 - Operating Instructions
44284-EN-171021
protocol.
RTU
Protocol
ABB Totalflow
Modbus RTU, ASCII
Bristol ControlWaveMicro
Modbus RTU, ASCII
Fisher ROC
Modbus RTU, ASCII
ScadaPack
Modbus RTU, ASCII
Thermo Electron Autopilot
Modbus RTU, ASCII
Parameters for the bus communication
The SITRANS LG260 is preset with the default values:
Parameter
Configurable Values
Default Value
Baud Rate
1200, 2400, 4800, 9600, 19200
9600
Start Bits
1
1
Data Bits
7, 8
8
Parity
None, Odd, Even
None
Stop Bits
1, 2
1
Address range Modbus
1 … 255
246
Start bits and data bits cannot be modified.
General configuration of the host
The data exchange with status and variables between field device and host is carried out via
register. For this, a configuration in the host is required. Floating point numbers with short prevision
(4 bytes) according to IEEE 754 are transmitted with individually selectable order of the data bytes
(byte transmission order). This "Byte transmission order" is determined in the parameter "Format
Code". Hence the RTU knows the registers of the SITRANS LG260 which must be contacted for the
variables and status information.
Format Code
Byte transmission order
0
ABCD
1
CDAB
2
DCBA
3
BADC
10.3 Modbus register
Holding Register
The Holding registers consist of 16 bit. They can be read and written. Before each command, the
address (1 byte), after each command, a CRC (2 byte) is sent.