CommunicationABB Control - AC 31 Page 7-51SBC 260400 R1001-b 06.991.2. Communication configurationMODBUS Communication, with the 40 and 50 series central units, is only allowed if the black07 SK 51 or 07 SK 53 cables are used.The serial interface of the 40 and 50 series central units have a default MODBUSconfiguration 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 : NoneIt is not necessary to configure the communication if your application uses these defaultparameters. However, any mode change requires a software serial interface configuration:Click on the "Launch PLC configuration tool" icon in the AC31GRAF software controlwindow 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 "Centralunit operative mode (CS31 MODBUS on CS31 bus)" line (see Figure 7-6)Figure 7-5 : The central unit configuration window in AC31GRAFFigure 7-6 : The central unit configuration window in AC31GRAFA change in the speed, stop bits, data bits or parity parameters is programmed with the SINITfunction. The usage of the SINIT function is not necessary when communication uses thedefault parameters.The MODBUS mode remains available, even if the central unit program is stopped (the frontswitch on OFF), when the black 07 SK 51 or 07 SK 53 cable is connected and the serialinterface is configured for MODBUS communication. The programming mode for tests andmodifications becomes available when the grey 07 SK 50 or 07 SK 52 cable is used.
