Lufft VENTUS-UMB - Communication in Modbus Mode

Operating Manual V25/09.2019 Ventus / Ventus-X / V200A
Chapter 20 Appendix 66
20.7 Communication in Modbus Mode
To enable the integration of Ventus wind meters into PLC and similar environments
communication with Modbus protocols is provided.
Measurement values are mapped to Modbus input registers. The range of available values is
basically the same as for the UMB protocol, including the translation into different unit systems
(metric, imperial …).
In the interest of safe and simple commissioning we do not use register pairs for floating point or
32 bit integers, as the use of register pairs is not described in the Modbus standard documents.
All measurement values are scaled to fit into 16bit integer registers.
20.7.1 Modbus Communication Parameters
The Ventus may be configured for MODBUS-RTU or MODBUS-ASCII.
For basic configuration the UMB Config Tool is used.
Note: If the Ventus has been configured for Modbus communication, analog output functions can
not be used!
If MODBUS-RTU or MODBUS-ASCII has been selected as communication protocol in the UMB
Config Tool, communication parameters are preset to 19200 Bd, even parity.
Modbus operating modes: MODBUS-RTU, MODBUS-ASCII
Baudrate: 19200 (9600, 4800 or less)
Interface settings 8E1, 8N1
Note: Ventus Modbus communication has been tested with 1 sec poll rate. Proper function of
the device will not be guaranteed for higher poll rates.
We suggest to set the poll rate to 10 sec or slower, because generally the update rate of the
measurement values is 10 sec or higher (except of the fast wind speed / wind direction
channels)
Anyway for most of the weather data significant changes should be expected more in the range
of minutes.
20.7.2 Addressing
The Modbus address is equal to the UMB address. Valid Modbus addresses are 1 to 247. If a
higher UMB address has been selected, the Modbus address will be set to 247.
20.7.3 Modbus Functions
The functions of Conformance Class 0 and 1 have been implemented, as far as they are
applicable for Ventus , i.e. all functions working on register level.
Conformance Class 0
0x03
Read Holding Registers
Selected configuration settings
0x16
Write Multiple Registers
Selected configuration settings
Conformance Class 1
0x04
Read Input Registers
Measurement values and status information
0x06
Write Single Register
Selected configuration settings
0x07
Read Exception Status
Currently not used (returns 0)
Diagnostics
0x11
Report Slave ID
(replies to broadcast address as well)