They Drive CMOS Logic Level Inputs

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. An example of an interface that could be installed is a CAN bus or an ETHERNET controller. In a computer system, SCSI-2 and SCSI-3 may use this specification to implement the physical layer for data transmission between a controller and a disk drive. EIA-485 specifies bidirectional, half-duplex data transmission. Although many applications use RS-485 signal levels, the speed, format, and protocol of the data transmission are not specified by RS-485. When the computer is to read data from the SMINI input ports, it simply tells the PIC16F877, which gathers the data from the 3 input ports, sets it up in the prescribed format, and transmits it bit-by-bit back to the computer. RS-232-in (7) - This green LED is lit whenever the data input is in the true state.

Brake (6) - This red LED is lit whenever power is being absorbed by the system due to dynamic braking, i.e. the motors are acting as generators during deceleration. RS-232-out (8) - This green LED is lit whenever the data output is in the true state. Without termination resistors, signal reflections off the unterminated end of the cable can cause data corruption. Only one end of the bus requires the resistor network. It requires minimal wiring and can share the wiring among several seats, reducing weight. RS-485 is also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. As a rule of thumb, the speed in bit/s multiplied by the length in metres should not exceed 108. Thus a 50-meter cable should not signal faster than 2 Mbit/s. Also check High Speed Ethernet (HSE) Data / specifications for Ethernet bus on this page.

The foreword to the standard references The Telecommunications Systems Bulletin TSB-89 which contains application guidelines, including data signaling rate vs. TSB-89A, Application Guidelines for TIA/EIA-485-A does not recommend using star topology. RS-422 and RS-485 Standards Overview and System Configurations, Application Report (pdf). RS-485 and RS-422 can interoperate with certain restrictions. RS-485 supports inexpensive local networks and multidrop communications links, RS485 standard using the same differential signaling over twisted pair as RS-422. Training (I) - This is the same connector type as used on the Limits, but a 8 pin Molex Tripeg connector. Industrial Ethernet and the "conventional" Ethernet both share the same physical and MAC levels , but use different protocols. RS-485 is used as the physical layer underlying many standard and proprietary automation protocols used to implement industrial control systems, including the most common versions of Modbus and Profibus. These characteristics make RS-485 useful in industrial control systems and similar applications. Selecting an interface standard that is no longer active and supported may make it hard to find both component and support. It may be used to control video surveillance systems or to interconnect security control panels and devices such as access control card readers.

It is also used in Digital Command Control (DCC) for model railways. DH 485 is a proprietary communications protocol used by Allen-Bradley in their line of industrial control units. In theatre and performance venues, RS-485 networks are used to control lighting and other systems using the DMX512 protocol. Digital communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. By using repeaters very large RS-485 networks can be formed. Each can work just fine with the C/MRI. With the 1x10 male header option, the CB485 can be used with solderless breadboards. The CB485 provides an RS-485 interface for microcontroller projects. The PCB-CB485 is a bare PCB to build the CB485 logic-level to RS-485 adapter. RS-485 signals are used in a wide range of computer and automation systems. RS-485, also known as TIA-485(-A) or EIA-485, is a standard, originally introduced in 1983, defining the electrical characteristics of drivers and receivers for use in serial communications systems. Multiple receivers may be connected to such a network in a linear, multidrop bus. The two connectors are paralleled to allow ease of daisy chaining between equipment on the network.