What is RS485 standard?

RS-485 is an industrial specification that defines the electrical interface and physical layer for point-to-point communication of electrical devices. The RS-485 standard allows for long cabling distances in electrically noisy environments and can support multiple devices on the same bus.

What is EIA-485 cable?

EIA-485 (formerly RS-485 or RS485) is an OSI model physical layer electrical specification of a two- wire, [1] half-duplex, multipoint serial connection. The standard specifies a differential form of signaling. Ideally, the two ends of the cable will have a termination resistor connected across the two wires.

What voltage is RS485?

Standard RS485 transceivers operate over a limited common mode voltage range that extends from –7V to 12V. In a commercial or industrial environment, ground faults, noise, and other electrical interference can induce common mode voltages that exceed these limits.

Is RS485 the same as Ethernet?

Often, terms like ”RS-485”, ”USB” and ”Ethernet” are interchanged as if they could be switched and do the same job. But in fact, the RS-485 standard is only a physical layer standard. It defines the electrical characteristics of the transmitter and the receiver.

What is the maximum distance for RS485?

4,000 feet
RS485 is popular for inexpensive local networks, multidrop communication links and long haul data transfer over distances of up to 4,000 feet. The use of a balanced line means RS485 has excellent noise rejection and is ideal for industrial and commercial applications.

Is RS485 a protocol?

RS-485 is still the most widely used protocol for POS, industrial, and telecom applications. The wide common-mode range enables data transmission over longer cable lengths and in noisy environments such as the floor of a factory.

Can you use Ethernet cable for RS485?

cat5e can be used up to 100m ethernet link. it has 4 twisted pairs so technically you should be able to use it for RS485 or RS422. if using 485, you need two twisted pairs so remaining 4 wires can be used for power. 485 cable should be shielded but twisted pairs of cat5e may work for some environments and baud rates.

Does RS485 need ground?

RS485 is the only differential interface allowing for robust data transmission over miles — long distances at reasonably high data rates of up to 100kbps.

Can we use CAT6 cable for RS485?

Cable construction: Cat5,Cat5e, and Cat6 24AWG twisted pair are very common cable types used for RS-485 systems. Adding shielding to the cable enhances noise immunity, and thereby increases the data rate for a given distance.

Is Modbus same as RS485?

Is Modbus the same as RS485? The answer is no, because both of these are relative concepts that need each other in order to fulfil their purposes. Modbus defines the protocol type and RS485 defines the signal level on the protocol.

When was TIA / EIA RS-422 and RS-485 created?

The industry standards TIA/EIA RS-422 (1994) and TIA/EIA RS-485 (1998) were developed by the Telecommunications Industry Association and Industries Alliance during the 90s. Both standards define a technology for data transmission largely free of interferences that has not existed in this form up to this time.

What’s the difference between EIA-485 and RS485?

EIA485 is also called the RS485 standard, but the term RS485 is out-dated. EIA-485 specifies bidirectional, half-duplex data transmission. Up to 32 transmitters and 32 receivers may be interconnected in any combination, including one driver and multiple receivers (multi-drop), or one receiver and multiple drivers.

What kind of bus interface does EIA-485 support?

A number of specifications use EIA-485 as the electrical standard, including SCSI-2, SCSI-3, BitBus, and Profibus. EIA/TIA-422 define a Balanced (differential) interface; specifying a single, unidirectional driver with multiple receivers (up to 32). RS-422 will support Point-to-Point, Multi-Drop circuits, but not Multi-Point [EIA485].

What is the maximum cable length for EIA / TIA-485?

EIA/TIA-485 drivers are allowed a smaller noise margin, with the minimum signal levels being volts and +1.5 volts. The maximum recommended cable length for both EIA/TIA-422 and EIA/TIA-485 networks is 1200 meters, which is greater than half a mile.