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 108. Thus a 50-meter cable should not signal faster than 2 Mbit/s." From Wiki.

Specifications:

• 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

Documentations:

• Wiki (Arduino RS485 Shield)
• Schematic

Package Includes:

• 1 x RS485 Arduino shield