| Abstract |
High-speed communications in automation and in links between variabie-speed drives confronts all the elements of communications with extreme problems. Because of the constraints placed on the baud rates of economically viable interface hardware and the program processing times required in cascaded microcomputers, considerable transport deadtimes result if software processing is not properly timed. In the case of short messages, the bus procedures have a considerable influence on the time required to transmit messages. The message contents can be kept short by omitting addresses for declared string locations in messages, and by using fixed-point notation and binary coding for words and addresses in numerical representation. User-configured communication data fields permit the use of relatively simple and short message contents even in system environments. Random data access via cascaded LANs and cascaded processor functions in systems with symbolic addresses can only be handled by special communications methods. The emerging standardization of low-costs LANs and serial interface, including LANs for drives, must take the special conditions prevailing for drive technology into account. |
