如今以太網(wǎng)交換機(jī)已廣泛應(yīng)用于通信行業(yè)中，在SOHO型企業(yè)中一個(gè)8端口的普通以太網(wǎng)交換機(jī)也許就能滿足需求，而在數(shù)據(jù)中心機(jī)房中則需要24端口或更多端口以及更高性能的以太網(wǎng)交換機(jī)。看似平常的以太網(wǎng)交換機(jī)卻蘊(yùn)含著五大突出特性，下面將一一探討。
更快的速度
最初的以太網(wǎng)規(guī)范描述了10Mbps標(biāo)準(zhǔn)，經(jīng)過多年發(fā)展速度已從百兆位上升到了千兆位，如今100Gbps以太網(wǎng)規(guī)范已出臺(tái)。更高速以太網(wǎng)標(biāo)準(zhǔn)的出臺(tái)也促使快速以太網(wǎng)交換機(jī)得到不同程度發(fā)展，快速以太網(wǎng)交換機(jī)支持全線速無阻塞交換以及端口自動(dòng)翻轉(zhuǎn)功能，采用全雙工工作模式避免了沖突檢測(cè)，提高了數(shù)據(jù)轉(zhuǎn)發(fā)速度。
支持VLAN
以太網(wǎng)基本架構(gòu)允許個(gè)人電腦、服務(wù)器和存儲(chǔ)設(shè)備都接入到同一臺(tái)以太網(wǎng)交換機(jī)上，這樣做的同時(shí)產(chǎn)生了一些問題，比如不同業(yè)務(wù)流量的廣播信息可能會(huì)泛洪到所有設(shè)備上，在產(chǎn)生額外流量的同時(shí)對(duì)于網(wǎng)絡(luò)管理來說也是不安全的。而以太網(wǎng)交換機(jī)支持虛擬局域網(wǎng)(VLAN)，可以在同一臺(tái)交換機(jī)上創(chuàng)建隸屬于不同業(yè)務(wù)需求的子網(wǎng)，不同VLAN上的設(shè)備盡管連接到相同的交換機(jī)上，但其MAC地址廣播卻被隔離在相同VLAN中，提高了管理性能，也增強(qiáng)了安全性。
以太網(wǎng)供電(PoE)
PoE將直流電源傳送到連接在以太網(wǎng)交換機(jī)上的設(shè)備，這樣可以大大簡(jiǎn)化設(shè)備部署。比如無線接入點(diǎn)、網(wǎng)絡(luò)攝像機(jī)和IP電話等通過以太網(wǎng)交換機(jī)傳送過來的直流電便可驅(qū)動(dòng)設(shè)備工作，不再需要獨(dú)立的電源模塊，使其可以比較方便的在任何有網(wǎng)絡(luò)連接的地方進(jìn)行工作。
服務(wù)質(zhì)量(QoS)
以太網(wǎng)交換機(jī)支持QoS功能，允許網(wǎng)絡(luò)管理員指定不同數(shù)據(jù)流量傳輸時(shí)的優(yōu)先級(jí)別。這樣就可以確保用戶在玩游戲或觀看視頻時(shí)沒有耗盡所有的帶寬，當(dāng)其他用戶使用網(wǎng)絡(luò)電話時(shí)，通過交換機(jī)上的QoS機(jī)制保障通話質(zhì)量。這為網(wǎng)絡(luò)管理帶來了便捷性，可以針對(duì)不同企業(yè)不同的業(yè)務(wù)需求降低非關(guān)鍵業(yè)務(wù)的優(yōu)先級(jí)，從而使關(guān)鍵業(yè)務(wù)流量快速順利的進(jìn)行傳輸。large, the wire coming out is too loose, and the loose wire will be broken like the stranded wire if it is not immediately stowed. Therefore, the normal startup and pulling out of qualified wire can be realized only if the slip is guaranteed to be within a certain deviation. The deviation between the actual value of the slip and the set slip should be controlled between 0.1 and -0.1m/s. The wire drawing machine operates at a constant speed after being input by AI2, and PLC controls the take-up frequency f = F1 F2 by detecting the calculated slip.
4、 Advantages of h2u series PLC in wire drawing machine
a) Fast instruction execution time
In 3335 steps of the whole program, a large number of complex instructions are used internally, such as PID, SPD, floating-point calculation, floating-point comparison, etc., and the monitored scanning time is only 6ms.
b) Fast communication speed and simple programming
The highest baud rate of Modbus communication is 38400bps, which makes the rapid adjustment of PID possible, while most brand minicomputers only reach 19200bps. The communication programming is simple, which can be realized with one RS command, and the other programs are completed by the system program. The communication control can be easi
