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This allows RS-485 to implement linear bus topologies using only two wires. RS485 avoids this issue which also allows for shielding of the cables to prevent noise. All of this allows you to speed up the VFD that controls the speed of that water pump. Let’s say you were monitoring a water pump filling a vessel. Let’s talk about what we now know about RS485. 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. Now there was certain instances I used STP wire for rs485 because I had a lot of devices connected in a long run chain (DMX512 lighting fixtures). SENSEWAY connects to WIRED PROs using custom-sized RS485 cables and a T connector. There is no standard connector for the protocol. Much like RS232, RS485 doesn’t have an actual standard connector. RS485 can handle up to 32 connected devices. RS232 could only handle one at a time.

On the other side we also have converter RS232 - RS485 ATC - 108N, via the RS232 port is connected to cash or other device with RS232 port. In summary, rs-485 cable, along with its 5-pair and rs485 to usb converters, plays a crucial role in enhancing the connectivity and flexibility of various control and measurement systems by enabling them to communicate seamlessly with modern computing technology. This device is essential when integrating modern digital devices or computers with legacy rs-485 devices in environments where a direct connection is not feasible or desirable. A Modbus RS485 connects a Master device to one or more Slave devices. This way, the lines will be biased to known voltages and nodes will not interpret the noise from undriven lines as actual data; without biasing resistors, the data lines float in such a way that electrical noise sensitivity is greatest when all device stations are silent or unpowered.

Without termination resistors, signal reflections off the unterminated end of the cable can cause data corruption. In order to avoid signal reflections, a 120 Ohm termination resistance must be fitted on each end of the main cable. The main cable must be no longer than 700 m! 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 end resistance must be used only at the ends of the main cable. If the total length of the main cable is less than 50 m termination resistances can be avoided at the ends of the main cable. Star and ring topologies are not recommended because of signal reflections or excessively low or high termination impedance. The value of each termination resistor should be equal to the cable characteristic impedance (typically, 120 ohms for twisted pairs). Otherwise a full 6 wire cable must be used. 3106A is what I typically use to wire balanced audio.

But You stated you are going to install this at a commercial setting, so it always better to use the worst case environment situations, and use shielded cable. The maximum RS485 cable length is typically listed as 1200 meters or about 4000 feet. The maximum number of devices that can be connected to a main cable is 32, including the Master. The cable to be used is a shielded twisted pair (telephone type). RS-485 supports inexpensive local networks and multidrop communications links, using the same differential signaling over twisted pair as RS-422. Multiple receivers may be connected to such a network in a linear, multidrop bus. It contributes to the reduction of transmission losses, thus increasing network reliability and comfort of heat consumers. Under some conditions it can be used up to data transmission speeds of 64 Mbit/s. 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. It bridges the gap between these different interfaces, allowing users to access and manage the data gathered by the industrial equipment via a standard, user-friendly usb port.