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Introduction to RS485 RS232 , RS422 , RS423 and RS485 are serial communication methods for computers and devices. RS232 is without doubt the best known interface, because this serial interface is implemented on almost all computers available today. But some of the other interfaces are certainly interesting because they can be used in situations where RS232 is not appropriate. We will conce
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RS485/RS232電纜選配和接線方式 在低速、短距離、無干擾的場合可以采用普通的雙絞線,反之,在高速、長線傳 輸時,則必須采用阻抗匹配 (一般為 120Ω)的 RS485 專用電纜(STP-120Ω(for RS485 & CAN ) one pair 18 AWG ),而在干擾惡劣的環(huán)境下還應采用鎧裝型雙 絞屏蔽電纜( ASTP-120 Ω(for RS485 & CAN) one pair 18 AWG )。在使用 RS485 接口時,對于特定的傳輸線路, 從 RS485 接口到負載其數(shù)據(jù)信號傳輸所 允許的最大電纜長度與信號傳輸?shù)牟ㄌ芈食煞幢龋?這個長度數(shù)據(jù)主要是受信號失 真及噪聲等影響所影響。理論上,通信速率在 100Kpbs 及以下時, RS485 的最 長傳輸距離可達 1200 米,但在實際應用中傳輸?shù)木嚯x也因芯片及電纜的傳輸特 性而所差異。在傳輸過程中可以采用增加中繼的方