USB to RS485 Converter USB to RS485 Adapter,CH340E USB to TTL
RS485 connector: to your RS485 device
No need external power, powered by USB port
Fully compliant USB 2.0 standard , backward compatible with USB1.1

• All kinds with RS485 port device parameter settings, data communication.
• LED display of communication data.
• Machine PLC data reading and writing.
• Monitoring data read and write, and PTZ control.
• Centralized control of household electrical appliances.
• Access Control System card.

USB to RS485 Converter Specification:

Support System: Windows XP , Vista, Windows 7/8
Supports baud rate range : 75bps – 115200bps , up to 6Mbps
Supports Plug , Play and hot-swap (USB side)
Better than using CH340E chip or similar chip to support the laptop USB port .
Communication distance up to 1.2KM, with anti-jamming performance of industrial site ;
Work temperature range: -40C ~ +85C
Communication distance :1200m(max)
Dimension:6.1×1.6×1.3cm
Color: Black en.wikipedia.org

RS-485 supports inexpensive local networks and multidrop communications links, using the same differential signaling over twisted pair as RS-422. It is generally accepted that RS-485 can be used with data rates up to 10 Mbit/s or, at lower speeds, distances up to 1,200 m (4,000 ft). As a rule of thumb, 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.