Features: Absolute using imported chips, industrial design, anti-interference ability, while using more effective mine design can be used in the industrial field and harsh field environments, the working temperature of -40 ? to + 85 ? transmission distance up to 1 kilometer (made with 850 meters of cable F1.5 tests recommended in the 800 meters, more than 800 m, please add repeaters). The module is fully considered mine design, long-distance transmission signal 485 in the wild, the module "Connected to the ground" terminal is connected to the earth, can play a very good anti-jamming and anti-lightning effect, more secure; it can not connect with the ground when the indoor short-distance transmission. Has a 120 ohm termination resistors, shorted R0to enable the termination resistor. Specifications: 3.3V with 5.0V power supply perfectly compatible. 3.3V with 5.0V signal perfectly compatible. Operating Temperature : -40 Degrees Celsius ~ + 85 Degrees Celsius. Size:42.8mm x 15.22mm x 0.8mm. Package Includes: 2pcs * TTL to RS485 485 to Serial UART AdapterHas RXD, TXD signal indicator light, monitor send and receive status,Support multi-machine communication, allowing access at up to 128 devices on the bus,The module can be hot swapped, the signal does not appear dead phenomenon. It has RXD, TXD signal indicator light, monitor send and receive status Using the 2.54 step design, easy standard secondary development. TTL to RS485 485 to Serial UART Adapter, Compatible with 3.3V and 5.0V power supply,Semi-hole pads, board module, thin PCB, with a thickness of 0.8mm. Only one on the entire power supply network, 3.3V and 5.0V, RS485 signal perfectly compatible with the automatic flow control module. Single chip microcomputer, RS485 TTL turn module, 485 turn UART serial port, level transfers, automatic flow control hardware.