中药配方颗粒自动发药机中的串行通信特殊技术

Special SerialCommunication Technique in Autodispense Compounded Chinese Medicine Granule Machine

系统采用西门子S7-200PLC控制中药配方颗粒自动发药机,遵循PLC内部固有的PPI通信协议,上位机采用VB连接OPC数据存取服务器的方法进行VB与PLC的串行通信,实现人机操作任务,这种通信方法与一般的自由通信协议相比,省略了PLC的通信程序编写,只需编写上位机的通信程序,节省PLC资源,缩短了系统开发周期.该通信技术已成功用于实践.

Auto-dispense Compounded Chinese Medicine Granule Machine is controlled hy SiemensS7- 200PLC. According to PPI communicating protocol, the authors use VB to connect the OPC data access server to realize the communication between VB and PLC. Compared with the ordinary free communication protocol, this way omits PLC communication programme, only programmes the communication procedure on PC, saves PLC resources and shortens researching cycle of system. This communication technique has been put into practice successfully.