UN1010-0001小型間接勵(lì)磁系統(tǒng),3BHE035301R1002使用進(jìn)展
Profibus DP與PFEA112的通信
3.13.1關(guān)于Profibus DP的一般數(shù)據(jù)
PFEA112中Profibus DP通信的目的是提供高速高級(jí)系統(tǒng)與PFEA112之間的通信鏈路。
Profibus DP是一種多點(diǎn)通信協(xié)議，旨在將PLC連接到傳感器（DP指“分布式外圍設(shè)備”）。
物理接口為RS 485（雙線電纜）。
最大傳輸速率為12 Mbit/s。
UN1010-0001小型間接勵(lì)磁系統(tǒng)該協(xié)議基于主從原則。PFEA112是從機(jī)。現(xiàn)場(chǎng)總線主控器始終輪詢從屬對(duì)象，這意味著輪詢將以固定的時(shí)間間隔進(jìn)行當(dāng)PFEA112沒有新數(shù)據(jù)可用時(shí)。每個(gè)從機(jī)的地址范圍為0到125。
Profibus要求消息格式、通信參數(shù)和錯(cuò)誤代碼
在所謂的類型文件（也稱為GSD文件）中提供了從機(jī)的個(gè)數(shù)（見附錄a.7
Profibus DP-PFEA112的GSD文件）。該文件隨后存儲(chǔ)在Profibus主機(jī)中。
啟動(dòng)時(shí)，Profibus主設(shè)備驗(yàn)證具有給定類型文件的從設(shè)備是否確實(shí)可用在公共汽車上。
3.13.2主從通信
主設(shè)備和從設(shè)備通過輸出緩沖器和輸入緩沖器進(jìn)行通信。主機(jī)讀取輸入緩沖區(qū)，并在每個(gè)掃描周期向輸出緩沖區(qū)寫入一次Profibus。
從機(jī)輪詢輸出緩沖區(qū)并更新輸入緩沖區(qū)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.
