PFEA113-65控制器,PFEA113-65配置手冊(cè)
PFEA113的Profibus DP通信3.13.1關(guān)于Profibus-DP的一般數(shù)據(jù)PFEA113中Profibus DP通信的目的是提供高速上級(jí)系統(tǒng)和PFEA113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(xiàn)電纜）。最大傳輸速率為12 Mbit/s。該協(xié)議基于主從原則。PFEA113是從機(jī)。
PFEA113-65控制器現(xiàn)場(chǎng)總線(xiàn)主機(jī)一直輪詢(xún)從機(jī)，這意味著輪詢(xún)以固定的時(shí)間間隔進(jìn)行當(dāng)PFEA113沒(méi)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需要消息格式、通信參數(shù)和錯(cuò)誤代碼在所謂的類(lèi)型文件（也稱(chēng)為GSD文件）中提供了從文件的個(gè)數(shù)（見(jiàn)附錄a.8）Profibus DP-PFEA113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(lèi)型文件的從設(shè)備確實(shí)可用在公共汽車(chē)上。3.13.2主從通信主設(shè)備和從設(shè)備通過(guò)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(xiě)入一次現(xiàn)場(chǎng)總線(xiàn)。從機(jī)輪詢(xún)輸出緩沖區(qū)并更新輸入緩沖區(qū)中的值。短線(xiàn)路高達(dá)1500 kbit/s<6.6 m。如果您使用的是12 Mbits/s，則應(yīng)避免使用短截線(xiàn)。如果使用EN 50 170規(guī)定的線(xiàn)路A，總線(xiàn)端接電阻組合如圖3-23所示，以確保線(xiàn)路上有定義的空閑狀態(tài)電勢(shì)。EN 50170中規(guī)定總線(xiàn)為A型線(xiàn)。應(yīng)避免使用B型線(xiàn)。介質(zhì)的物理性質(zhì)如表3-3和表3-4所示。Profibus DP Communication with PFEA113
3.13.1 General Data about Profibus DP
The purpose of the Profibus DP communication in PFEA113 is to provide a high speed
communication link between superior systems and the PFEA113.
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 PFEA113 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 PFEA113.
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.8
Profibus DP - GSD File for PFEA113). 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.Stub lines up to 1500 kbit/s < 6.6 m.
If you are using 12 Mbits/s you should avoid stub lines.
If you are using line A as specified by EN 50 170, the bus terminating resistance combination
is as shown in Figure 3-23, so that a defined idle state potential is ensured on the line.
The bus line is specified in EN 50170 as line type A. Line type B should be avoided.
The physical properties of the media are shown in Table 3-3 and Table 3-4.
