User Manual
Precipitation Sensor rain[e]H3 with Ethernet
Id-No. 00.15184.540 020
rain[e]H3
Precipitation Sensor
Manual
11
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).
11.1
Data Encoding
MODBUS uses the “big-endian“ format for addresses and data. This means that if a value is transmit-ted 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 (32 bit or 64 bit):
Register size value
32 - bits 0x12345678 is transmitted in the order: 0x12 0x34 0x56 0x78.
To obtain the real measuring value, divide the received register value by the divisor.
Values of -9999 (16 bit value) or -9999999 (32 bit value) indicate an internal sensor error.
11.2
Device Address
The addresses 1...247 are permitted for Modbus.
11.3
Standard Configuration - Default
Baud rate:
19200 Baud
Address:
Each sensor type (or family) has its own default address.
Default addresses of the LAMBRECHT sensors:
Address
Sensor
1 Wind speed
2 Wind direction
3 Precipitation rain[e]
4 THP
5 EOLOS IND · u[sonic]WS6
6 com[b]
7 PREOS
8 ARCO
9 u[sonic]
10 Pyranometer 2nd Class
11 Secondary standard Pyranometer
12 PT100 to Modbus converter (temperature)
13 u[sonic]WS7
Byte frame according to MODBUS standard for RTU mode:
8E1 (1 start bit, 8 data bits, 1 parity bit (even parity), 1 stop bit)
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