In Europe, communication between telecontrol master stations and substations is generally based on standardised IEC 60870-5 protocols. Standard 101 has been defined for serial communication and standard 104 for IP-based communication. Beckhoff supports these standards with PLC libraries for TwinCAT automation software.
The slave implementations for the 101 and 104 protocols, developed by Beckhoff as pure PLC libraries, are already being used in a wide range of applications. Embedded PCs from the CX family are generally used as CPUs. However, some applications require a device to simultaneously operate in slave and master mode. This device acts as a slave connected to a master station and, at the same time, as a master for subordinate devices. Therefore, a new PLC library referred to as TwinCAT PLC IEC 60870-5-104 master providing master functionality for the 104 protocol has been developed. The slave and master process images can be easily synchronised.
TwinCAT automation software integrates real-time control with PLC systems, NC axis control and a programming environment in a single, dynamic package. The software PLC/NC/CNC is embedded in Microsoft operating systems Windows NT/2000/XP. Programming is based on the globally-recognised IEC 61131-3 standards. TwinCAT links to all common fieldbuses and PC interfaces for I/O signals.