Manual
Combined Wind Sensor ARCO-Modbus
(14581) ARCO-Modbus
Manual
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Modbus protocol
The Lambrecht meteo Modbus sensors and the met[LOG] follow the specifi cation of the Modbus organization: "MODBUS
APPLICATION PROTOCOL SPECIFICATION V1.1b3". (See www.modbus.org).
6.1
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 signifi cant byte" is sent fi rst. For values that go beyond one register (e.g.
32 bit) this is not clearly specifi ed 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.
6.2
Device address
The addresses 1...247 are permitted for Modbus.
6.3
Standard confi guration - 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
6 com[b]
7 PREOS
8 ARCO
9 u[sonic]
10 Pyranometer 2nd Class
11 Secondary standard 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)
6.4
Modbus command set
The LAMBRECHT Modbus sensors support the following commands:
• Read Input Register" command:
0x04 (Read out measured data)
• Write Multiple Register" command:
0x10 (Write sensor data)
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