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5 Communication with 16131.5
5.1 Modbus-protocol
The Lambrecht meteo Modbus sensors and the met[LOG] follow the specification of the Modbus
organization: "MODBUS APPLICATION PROTOCOL SPECIFICATION V1.1b3"
(see www.modbus.org).
5.2 Data encoding
MODBUS uses the "big-endian" format for addresses and data. This means that if a value is
transmitted with a number format that is larger than a single byte, the "most significant byte" is sent
first. For values that go beyond one register (e.g. 32 bit) this is not clearly specified for the Modbus. In
these cases (32 bit or 64 bit) the LAMBRECHT Modbus sensors follow the big-endian number format.
Example Big-Endian:
Register size value
16 - Bits 0x1234 is transmitted in the order: 0x12 0x34.
Example big-endian (32bit or 64bit):
Register size value
32 - Bits 0x12345678 is transmitted in the order: 0x12 0x34 0x56 0x78.
5.3 Device-address
The addresses 1...247 are permitted for Modbus.
Warning: Using the same Modbus address for more than one device will lead to irregular behaviour of
the entire network.
5.4 Standard configuration - default
Baud rate:
19200 Baud
Address:
Each sensor type (or family) has its own default address.
Table 5.4.1
Default addresses of the LAMBRECHT sensors
Address
Sensor
1 Wind speed
2 Wind direction
3 Precipitation rain[e]
4 THP
5 EOLOS IND
6 com[b]
7 PREOS
8 ARCO
9 u[sonic]
10 Pyranometer 2nd Class
11 Secondary standard Pyranometer, First Class Pyranometer
12 PT100 to Modbus converter (temperature)
Byte frame according to MODBUS standard for RTU mode:
8E1 (1 start bit, 8 data bits, 1 parity bit (even parity), 1 stop bit)
