6
Ziehl-Abegg MODBUS-RTU Description
6.1
Introduction
The Ziehl-Abegg device series are equipped with an RS-485 interface (A [D+], B [D-], GND). The
device can be controlled and parameterised by the MODBUS-RTU protocol by using this interface.
The MODBUS-RTU protocol implementation of the device complies with the standards as described
in the "MODBUS Application Protocol Speci
fi
cation 1.1". Not all the function codes contained therein
are implemented in the device. The device basically supports all functions which are available for
holding and input registers.
6.2
Data model and access options
The application data of the device are organised so that access to them is possible with the MODBUS
function for 16-bit registers.
Data items which have a smaller word width internally are extended to 16 bits, data items which have
a larger word width are distributed to 2 registers. The device does not support bit-oriented data items.
The MODBUS access to the application data is gained with the following MODBUS functions for
registers:
•
Read Input register (function code 4)
•
Read Holding register (function code 3)
•
Write Single register (function code 6)
•
Write Multiple registers (function code 16)
Les- und schreibbare Daten
(z.B. Parameter)
Lesbare Daten
(z.B. Istwerte)
Holdings Registers
Input Registers
R/W
R
MODBUS Zugriff
Applikationsdaten
Picture 14: data model
The application data are arranged completely in the Holding Register and the Input Register section
respectively beginning at MODBUS register address 0. An exception message is output on exceeding
the register range.
6.3
Alternative slave-addressing
Addressing is performed by the built-in terminal, an external terminal or a PC with the appropriate
software (e.g. NETcon).
There is a menu item for this in the "IO Setup" menu group. The address is programmed to the highest
possible MODBUS address (247) in the factory setting.
The Ziehl-Abegg ECblue fans with AM-MODBUS modules also offer the possibility of automatic
addressing in the connection with our MB/TCP gateway. The line ID must be connected additionally
for this.
Technical information
MODBUS RTU System
–
model series
Ziehl-Abegg MODBUS-RTU Description
R-TIL08_01-GB 1215
Part.-No.
13/16