Operating instructions type-lines CXE/AVC (E)
Date 0917
TBL02_13-GB 0917
Art.-Nr. 00153342-GB
Seite 53 / 63
13.5 Network for several divices by MODBUS
13.5.1 MODBUS - RTU (Remote terminal unit))
It is possible to network several devices with each other. .
The device uses the MODBUS-RTU as the protocol for the RS-485 interface. The communications parameters
are permanently set to 19200 baud, 8 data bits, EVEN parity, 1 stopbit, (8E1).
A maximum of 247 stations can be connected with each other. The device address (Device-ID) is factory set to the
highest available MODBUS address:
247
This address is reserved for operation with an external terminal model A-XG.. and should not be occupied with anything
else.
The addresses of the individual units must be continuously numbered beginning with „1“. No address may be allocated
twice.
MODBUS address adjustable from 1-247
Address 247 = preprogrammed for an external terminal
When using an external AXG.. terminal, the interface is assigned and can not be employed for anything else
13.5.2 External display
The device uses MODBUS as the protocol for data exchange with an external AXG... display During this, the external
display is the MODBUS master. In this case, the interface is occupied and cannot be utilized for anything else.
The external display uses the
function code 105
(User Code) for the data exchange. This function code should
therefore be avoided in a MODBUS system with other stations.
13.5.3 Reading and writing parameters
The device supports reading and writing processes for MODBUS Holding Registers (3). The start address is 1; the
number of registers depends on the device. If the allowable start address or number is exceeded, the device answers
with an exception code. The description of the register is device dependent and can be requested from Ziehl-Abegg
service for the device/version concerned.