UN1010-0001小型间接励磁系统,3BHE035301R1002使用进展
Profibus DP与PFEA112的通信
3.13.1关于Profibus DP的一般数据
PFEA112中Profibus DP通信的目的是提供高速高级系统与PFEA112之间的通信链路。
Profibus DP是一种多点通信协议，旨在将PLC连接到传感器（DP指“分布式外围设备”）。
物理接口为RS 485（双线电缆）。
最大传输速率为12 Mbit/s。
UN1010-0001小型间接励磁系统该协议基于主从原则。PFEA112是从机。现场总线主控器始终轮询从属对象，这意味着轮询将以固定的时间间隔进行当PFEA112没有新数据可用时。每个从机的地址范围为0到125。
Profibus要求消息格式、通信参数和错误代码
在所谓的类型文件（也称为GSD文件）中提供了从机的个数（见附录a.7
Profibus DP-PFEA112的GSD文件）。该文件随后存储在Profibus主机中。
启动时，Profibus主设备验证具有给定类型文件的从设备是否确实可用在公共汽车上。
3.13.2主从通信
主设备和从设备通过输出缓冲器和输入缓冲器进行通信。主机读取输入缓冲区，并在每个扫描周期向输出缓冲区写入一次Profibus。
从机轮询输出缓冲区并更新输入缓冲区中的值。
Profibus DP Communication with PFEA112
3.13.1 General Data about Profibus DP
The purpose of the Profibus DP communication in PFEA112 is to provide a high speed
communication link between superior systems and the PFEA112.
Profibus DP is a multidrop communication protocol intended to connect PLCs to sensors (DP
means “Distributed Peripherals”).
The physical interface is RS 485 (two wire cable).
The maximum transfer rate is 12 Mbit/s.
The protocol is based on a master-slave principle. The PFEA112 is a slave. A Profibus master
polls the slaves all the time, that means the polling is going on with a fixed time interval even
when no new data is available from the PFEA112.
Each slave has an address in the range 0 to 125.
Profibus requires that the message format, communication parameters and error codes
of slaves are made available in a so called type file, also known as GSD file (See Appendix A.7
Profibus DP - GSD File for PFEA112). This file is then stored in the Profibus Master.
At start-up the Profibus Master verifies that the Slave with the given type file is indeed available
on the bus.
3.13.2 Master-slave Communication
The Master and the slave communicate via an output buffer and an input buffer.
The master reads the input buffer and writes to the output buffer once every scan cycle for
Profibus.
The slave polls the output buffer and updates values in the input buffer.
