With noisy environments (our sites?) using the shield as ground is not always the most effective solution. This helps reduce the effects of electromagnetic interference (EMI) and noise, making it suitable for noisy industrial environments. Digital communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. The EIA once labeled all its standards with the prefix "RS" (Recommended Standard), but the EIA-TIA officially replaced "RS" with "EIA/TIA" to help identify the origin of its standards. The EIA has officially disbanded and the standard is now maintained by the TIA as TIA-485, but engineers and applications guides continue to use the RS-485 designation. If A is negative with respect to B, the state is binary 1. The reversed polarity (A positive with respect to B) is binary 0. The standard does not assign any logic function to the two states. RS-485 transmits data using differential signalling, where two complementary signals, A and B, are sent over twisted-pair cables. 100 ohms, Cat 5 cables almost meets the electrical requirements for RS-485 cables.

RS-485 is also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. RS-485 signals are used in a wide range of computer and automation systems. This allows RS-485 to implement linear bus topologies using only two wires. For fixed laying Maximum shielding capacity in accordance with EMC requirements, Cable for Modbus bus systems, SUCOnet P, Modulink P, VariNet-P, Dry and damp environments, Suitable for various bus systems based on RS485 / RS422. Multiple receivers may be connected to such a network in a linear, multidrop bus. The ideal RS485 network requires a dedicated wire for ground. But these are signal wires and the network always requires a return path. The shield works as a "drain" for any noise that could be picked up by the RS485 network and "drain" it to ground. Combined with the right cables, they are going to guarantee the creation of stable and functional RS485 networks. The twin consists of two conductors that are twisted together. The shielding may be braided (be formed by a mesh of thin conducting wires) or be a foil (consisting of a sheet of metal wound around the conductors): the two types are equivalent.

For example, Belden 3105A cable can be specified, but different types of cable with equivalent characteristics can be used. Both types of shielding are OK. Because they are produced in such large quantities, Cat 5 cables are relatively inexpensive, often less than half the price of specialty RS-485 cabling. In practice, Cat 5 cables have been used successfully in many installations, but there are some concerns. And even worse, if you have a non opto-isolated device installed on that network, any noise could "drain" to ground through the device itself instead of flowing through the ground terminal at the end of the line, damaging the device in the process! Redlion sells a cable that goes from RJ45 connector on one end to bare wires on the other end. End of line termination resistor (120 ohm 1/4 watt) to be installed at both ends of network. In order to avoid signal reflections, it is required to turn on the 120 ohm terminal resistance at ends of the communication cable. In order to increase the extent of the Modbus network, repeaters can be used; and signal amplifying and regenerating devices provided with two communication ports that transfer to each what they receive from the other.

By using repeaters very large RS-485 networks can be formed. Using a repeater, the main cable is divided into different segments, each of which can be up to 700 m in length and connect 32 devices (this number includes the repeaters). The main cable must be no longer than 700 m! If on the other hand each terminal can accept only a single cable, rs485 cable a proper branch must be created using three auxiliary terminals for each instrument to be connected. Communicating with devices that can talk via RS485 using any of the protocols/drivers supported by Redlion Crimson Software. You can actually use any of the four combinations for 2 wire RS485 wiring. Under some conditions it can be used up to data transmission speeds of 64 Mbit/s. RS-485 is a standard that defines the electrical characteristics of a serial data transmission system. The diagram below shows potentials of the A (blue) and B (red) pins of an RS-485 line during transmission of one byte (0xD3, least significant bit first) of data using an asynchronous start-stop method.