The Design And Implement Of Digital Dispatching Switch

With the rapid development of the technology of digital time division switching, the digital time division switching technology has been applied in wide scale. It applies not only at large-amount pabx,but also at special pabx.The special switches working at the corporations related to electric power, railway, petroleum, chemical plant, mining, fire protection and so on are mainly bearing important dispatching works. We often call this special designed switch with dispatching works as Digital Dispatching Switch. The digital dispatching switch discussed in this text mainly work at electric power system such as electric power supply companies,electric power plants and transformer stations. At present, most transformer stations of electric power system have realized nobody on duty, then these digital dispatching switches with highly reliable,low cost and new services have more market demands. Recently, as new technologies wide applications and technologies with high cost before are universally used in the design of small-type system, it becomes possible for producing one kind of digital dispatching switch with small- capacity,high performance and low cost. The digital dispatching switch discussed in this text adopts full-separate control technology and the digital time division switching technology. This switch consists of 8 sub-systems, each sub-system supplies exchange capability of 256×32 time slot, then 8 sub-systems can make up one unblocked exchange network with the exchange capability of 256×256 time slot. Each sub-system's capacity can reach 128 ports, the max capacity of this switch can reach 1024 ports. The control system adopts 80C652 microcomputer system on a chip. Multi–microcomputer communicate through SBUSII (serial communication bus ) with CSMA/CD protocol. The master clock is not appointed, it is selected automatically by software during running period. The extension sub-systems is discussed in this text mainly.This digital dispatching switch supports various interfaces such as line interface, 2-wire trunk, EM trunk and various signaling (Chinese NO.1 signaling, NO.7 signaling, MFC etc.) for connecting other switches. In this system, the applications of ASIC predigest the system structure and enhance the system reliability.