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. SATA Cables: The Industry Standard for Connecting Storage Devices SATA stands for Serial Advanced Technology Attachment and is a standard attachment standard that is widely used for connecting various peripherals such as hard disks, optical drives and solid-state drives to a computer motherboard. The standard is jointly published by the Telecommunications Industry Association and Electronic Industries Alliance (TIA/EIA). 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. It does not specify or recommend any communications protocol; Other standards define the protocols for communication over an RS-485 link. RS-485 does not define a communication protocol; merely an electrical interface. It also defines three generator interface points (signal lines); A, B and C. The data is transmitted on A and B. C is a ground reference.

It holds true for electrical interface standards as well. RS-422 and RS-485 Standards Overview and System Configurations, Application Report (pdf). 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, what is rs485 cable multidrop bus. When using the default RS485 receivers with an input resistance of 12 kΩ it is possible to connect 32 devices to the network. Twisted pair structure: Rs485 anti-interference cable has a twisted pair conductor structure. Rs485 cables not only vary in the structure of the core but also in the number of twisted pairs. The left side of the image shows the structure of the twisted pair cable, including copper wire, shielding, and insulation. With Modbus, BACnet and Profibus, A/B labeling refers A as the negative green wire and B as the positive red wire, in the definition of the D-sub connector and M12 circular connector, as can be seen in Profibus guides. Ring topology arranges network nodes in a circular configuration where each node connects to two others, forming a closed loop.

While four-wire full-duplex exists, it is less prevalent in current applications, with the two-wire half-duplex configuration being the predominant wiring method in use today. RS-485 is also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. It may be used to control video surveillance systems or to interconnect security control panels and devices such as access control card readers. These fully operational NUC systems come with a variety of differences in specifications. PLC systems are used to monitor and control operations, while HMI network systems allow interaction with machinery and control them. Different topology designs suit different network needs and applications, affecting performance, reliability, and scalability. TSB-89A, Application Guidelines for TIA/EIA-485-A does not recommend using star topology. Among various topological structures, the Daisy Chain topology is considered the optimal choice for RS-485 due to its minimal impact on signal integrity. The entire daisy chain network is ultimately connected to a PLC (Programmable Logic Controller), facilitating data exchange between multiple devices and the central control system. The outer layer of aluminum foil covers the entire conductive core, serving to counteract high-frequency interference.

RS-485 serves as a physical layer for the AES3 digital audio interconnect. Cable jacket: Made from high-quality PVC, the outermost jacket layer has high elasticity, helping to protect the cable from strong environmental impacts. RS485 drivers automatically return to their high impedance tri-state within a few microseconds after the data has been sent. Because of this RS485 and the others can be used in situations with a severe ground level shift of several volts, where at the same time high bit rates are possible because the transition between logical 0 and logical 1 is only a few hundred millivolts. Therefore RS485 will be in use for many years in the future. 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. This has been done to avoid reflections of signals. B line (or Data-), handles the complementary differential signals.