RS485 Communication Module: Pinout, Cable and Wiring

RS485 Pinout

The RS485 is required to enable the Modbus communications to function on Model 77x-type products. This module is required when the RM1000, RM2000, or other Modbus-capable device is used with 77x-type products.

An RS485 system should ideally consist of a single linear cable (with no branching) with 120-ohm resistors linked across the two wires at each end. RS485 can handle line lengths of over 1 km and rates of over 10 Mbits per second.

RS485 Wiring Diagram

Three conductors and a shield are required for RS485 to work. Although many people believe it is a two-wire network, it is not. The RS485 Differential voltage signal is carried on two conductors. The Shield is only connected to the earth/ground on one end and provides noise shielding.

• Optical isolation from line potentials

• Powered by the 77x product

• RS-485 compliant bus drive capability

• Remote reset input connection

• Power connection for the Model RM1000

• The RS485 can be utilized in a variety of applications.

• Establish communications in LED displays.

• Data reading and writing in PLC machines

• Device parameter adjustments and data transfer via the RS485 connection.

• Control of household electrical appliances from a central location

RS232 is more than able to perform for a short distance and low data speed requirements. RS232 has a transmission speed of 1Mb/s up to 15M. However, RS485 has a data transmission speed of up to 10Mb/s for a distance of 15M. At the maximum of 1200M, RS485 transmits at 100Kb/s.

With multi-drop (many devices on the same bus) and extensive cabling lengths, it's easy to see why the RS485 is so popular in the industrial and automation worlds. RS-485 is also used in theater applications, where a large number of devices are spread out across a large area.

Furthermore, the RS-485 standard's noise immunity makes the interface extremely adaptable. Engineers are employing it not only for lengthy cabling distances but also in industries such as the automotive industry, where it is unknown what noise will be encountered in the end product. Because it may be used at high speeds, over long distances, in electrically loud settings, and with multiple devices on the same bus, RS-485 is a good choice for most serial interface applications.

Littelfuse, Inc is an American electronic manufacturing company headquartered in Chicago, Illinois. The company primarily produces circuit protection products but also manufactures a variety of electronic switches and automotive sensors. Littelfuse was founded in 1927. In addition to its Chicago, Illinois, world headquarters, Littelfuse has more than 40 sales, distribution, manufacturing, and engineering facilities in the Americas, Europe, and Asia.