Commissioning
6.4 Modbus configuration for SITRANS SL
SITRANS SL
106 Operating Instructions, 12/2010, A5E01132948-04
6.4 Modbus configuration for SITRANS SL
6.4.1 Modbus settings
Modbus settings are configurable via LUI. Detailed information about the parameters can be
found in the Generic Modbus device specification.
Default values of the Modbus settings are stored in the ModbusConfig.xml. If these
parameters are modified by customers, the modified paramters will be stored in the
EEPROM and then be effective.
Table 6- 1 Modbus settings
Setting parameter Default LUI
Slave ID 1 to 247 1 X
Baud Rate 300 – 115200 19200 X
Parity None, Even, Odd None X
Transmission mode RTU + ASCII RTU X
RTU frame timeout 0 - 600000 ms 50 ms X
ASCII frame timeout 50 - 600000 ms 1000 ms X
Application answer
timeout
50 - 10000 ms 1000 ms X
Minimum answer delay
time
5 - 1000 ms 20 ms X
Data Bits 7, 8 8 X
Stop Bits 1, 2 1 X
6.4.2 Byte and word ordering
● The interpretation of the data field within the Modbus RTU protocol is according to the
original Modbus Application Protocol Specification "big endian Mode".
● Given that the Modbus RTU message protocol is "big endian", in order to successfully
exchange a 32 bit data type via a Modbus RTU message, the endianness of both master
and slave must be ensured. SITRANS SL allows specific selection of byte orders, so you
must take care that both units are set to the same byte order.
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