ABB AC 31 - 1.2. Communication configuration

Communication
ABB Control - AC 31 Page 7-5
1SBC 260400 R1001-b 06.99
1.2. Communication configuration
MODBUS Communication, with the 40 and 50 series central units, is only allowed if the black
07 SK 51 or 07 SK 53
cables are used.
The serial interface of the 40 and 50 series central units have a
default MODBUS
configuration
with the following parameters:
- Mode:
MODBUS slave 1 unit
- Transmission speed : 9 600 Bauds
- Number of stop bits : 1
- Number of data bits : 8
- Parity : None
It is not necessary to configure the communication if your application uses these default
parameters. However, any mode change requires a software serial interface configuration:
Click on the
"Launch PLC configuration tool" icon in the AC31GRAF software control
window
 If you use the serial interface: Select the MODBUS address from the list of the
"Communication mode" line (see Figure 7-5)
 If you use the CS31 connection: Select the MODBUS address from the list of the "Central
unit operative mode (CS31
MODBUS on CS31 bus)" line (see Figure 7-6)
Figure 7-5 : The central unit configuration window in AC31GRAF
Figure 7-6 : The central unit configuration window in AC31GRAF
A change in the speed, stop bits, data bits or parity parameters is programmed with the SINIT
function
. The usage of the SINIT function is not necessary when communication uses the
default parameters.
The MODBUS mode remains available, even if the central unit program is stopped (the front
switch on OFF), when the black 07 SK 51 or 07 SK 53 cable is connected and the serial
interface is configured for MODBUS
communication. The programming mode for tests and
modifications becomes available when the grey 07 SK 50 or 07 SK 52 cable is used.