DFRobot RS485 Shield for Arduino 擴展板｜ 工業級通訊，輕鬆連接 PLC、DCS 等設備

商品說明

RS485 是用於長距離、抗干擾和可靠通訊的工業標準。 Arduino RS485 擴展板 專為Arduino Uno 開發板設計。它將 UART/串行協定轉換為 RS485協定。這款 RS485 擴充板可讓 Arduino 與工業設備通訊。

RS-422 只有一個驅動電路，且無法關閉，而 RS-485 驅動器則採用三態邏輯，允許單一發射器停用。這使得 RS-485 能夠僅使用兩根電線實現線性總線拓撲。位於一組 RS-485 電線上的設備可互換稱為節點、站或設備。

• 整合標準RS485端口、迷你RS485端口、RS485接頭
• 提供焊接區域，充分利用空閒空間，方便DIY設計。
• 自動模式與手排變速模式之間切換，擴大了適用範圍。
• 除了 Tx/Rx 介面之外，當需要對 Arduino 進行編程時，還有一個開關可以阻止/停用此屏蔽。
• 沉金PCB。背部長針腳適配大多數Arduino控制器。

什麼是RS485？

RS-485 可以設定低成本的區域網路和多點通訊鏈路。它提供 35 Mbit/s 的資料傳輸速度，傳輸距離可達 10 米，傳輸速度可達 100 kbit/s，傳輸距離可達 1200 公尺。由於它使用雙絞線上的差分平衡線路（類似 RS-422），因此可以跨越相對較遠的距離，最遠可達 1200 公尺（4000 英尺）。根據經驗，傳輸速度（以位元/秒為單位）乘以長度（以公尺為單位）不得超過 10^8。因此，50 公尺長的電纜訊號傳輸速度不應超過 2 Mbit/s。 （取自維基百科）

注意：接線端子的螺絲十字頭樣式可能略有不同。兩種版本均可使用標準十字螺絲起子完美安裝。

 RS485 Shield 規格

• 電源模組：+5V
• 模組尺寸：55mmx53mm(2.16″x2.08″)
• 16個數位IO埠（包括一個I2C介面）
• 6個模擬IO連接埠和電源
• 操作和編程模式切換
• 自動、手動收發模式切換（手動收發模式時，啟用端為第2個數位IO口）
• 收發器指示燈
• 標準RS485介面、迷你RS485介面、RS485接腳
• 焊接區域
• 重設開關
• DFRobot RS485系列感測器的PH2.0感測器介面：URM04超音波感測器

RS485 Shield 文件資料

• 維基百科（Arduino RS485 擴充板）
• 示意圖 

RS485 Shield 出貨清單

• RS485 Arduino擴展板 x1

技術補充（英文）

以下為原廠英文技術說明，提供進階使用者參考。

RS485 is an industrial standard for long-distance, anti-interference, and reliable communication. The Arduino RS485 shield, specially designed for the Arduino Uno board. It converts UART/Serial protocol to the RS485 protocol. This RS485 board allows Arduino talk to industrial devices.

In contrast to RS-422, which has a single driver circuit that cannot be switched off, RS-485 drivers use three-state logic allowing individual transmitters to be deactivated. This allows RS-485 to implement linear bus topologies using only two wires. The equipment located along a set of RS-485 wires is interchangeably called nodes, stations, or devices.

Integrated a standard RS485 port, a mini RS485 port, RS485 headers
Provide the welding areas to make full use of the free space. And more importantly, it’s convenient for your DIY design.
Switch between automatic mode and manual transmission mode, which expands the scope of application.
Besides Tx/Rx interface, there is a switch to block/disable this shield, when Arduino needs to be programmed.
Gold immersion PCB. Long pins on the back adapt to most Arduino controllers.
What is RS485?

“RS-485 enables the configuration of inexpensive local networks and multidrop communications links. It offers data transmission speeds of 35 Mbit/s for distances up to 10m and 100 kbit/s up to 1200 m. Since it uses a differential balanced line over twisted pair (like RS-422), it can span relatively large distances up to 1,200 m (4,000 ft). A rule of thumb is that the speed in bit/s multiplied by the length in meters should not exceed 10^8. Thus a 50-meter cable should not signal faster than 2 Mbit/s.” From Wiki.

Note: The screws for the terminal blocks may have slightly different cross-head styles. Both versions work perfectly with a standard Phillips head screwdriver.

Specification for RS485 Shield

• Power module: +5V
• Module size: 55mmx53mm(2.16″x2.08″)
• 16 digital IO ports (including an I2C interface)
• 6 analog IO ports and power
• Operation and programming mode switch
• Automatic and manual transceiver mode switch (When in manual transceiver mode, the enable end is the 2nd digital IO port)
• Transceiver indicating LED
• Standard RS485 interface, mini RS485 interface, and RS485 pins
• Welding area
• Reset switch
• PH2.0 sensor interface for DFRobot RS485 series sensor: URM04 Ultrasonic sensor

資料來源：DFRobot 官方，經實測整理後彙整