RS-422/RS-485 Switch, Termination Switch

RS-422/RS-485 Switch

This switch controls the positive threshold voltage for the Positive Threshold LED only. When the switch is in the RS-422 position, the positive threshold is +7 volts. When it is in the RS-485 position, the positive threshold is +12 volts. This switch has no effect on the Data LED, the Threshold Pot, or on the Negative Threshold LED.

Termination Switch

In some cases RS-422 and RS-485 pairs are terminated. This termination is usually needed only for long or high speed networks. Terminations usually consist of a 100 ohm one-half watt resistor located at each end of the network. In some complicated multi-drop networks it may be hard to determine exactly were the “ends” are. A 100 ohm one-half watt termination resistor is included in the 485T. It may be helpful if you are testing an existing network with no terminations and want to see what happens if you terminate it at one point. Normally, you should leave this switch OFF (down).

Power

The 485T will work from a nine-volt battery or from 12 VDC through the 2.5 mm jack marked DC Power 12VDC IN. When you plug in the external power supply (available from B&B Electronics as the Model 485PS) the battery is automatically disconnected.

RS-232 Data Out Connector

This is a standard DB-25S RS-232 connector. When the DATA LED is blinking, any RS-422/485 data on the A & B inputs is converted to the RS-232 format and output on pin 2. You can connect this to a device that has an RS-232 port and can read your data. Be sure you turn the threshold pot all the way down (clockwise) to zero. For use on standard ASCII data B&B Electronics sells a program called BreakOut II that will turn a PC into a serial data monitor. With it and a PC you can monitor data on your RS-422/485 network.

NOTE: If your data is garbled you may have the A and B lines connected backwards or the threshold pot may not be all the way down to zero. It is also possible that the RS-422/485 signal may be too weak.

8Documentation Number 485T1995 Manual

B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350

PH (815) 433-5100 -- FAX (815) 433-5105

485T specifications

B&B Electronics has been a prominent player in the field of industrial connectivity solutions, and one of their notable products is the 485T. The 485T is a robust serial communication device designed specifically for converting RS-232 signals to RS-485. This device is particularly valuable in environments that necessitate reliable signal transmission over extended distances, which is where traditional RS-232 connections typically fall short.

One of the standout features of the B&B Electronics 485T is its ability to support communication over long distances of up to 4,000 feet. This makes it an ideal solution for applications in industrial settings, where distances between devices often exceed the limitations of standard serial connections. With data rates of up to 115.2 kbps, the 485T ensures that information can be transmitted swiftly and efficiently, making it suitable for various real-time monitoring and control applications.

The 485T incorporates advanced technologies that enhance its performance and reliability. For instance, it features built-in surge protection, which safeguards the device and connected equipment from voltage spikes and transient events. This is crucial in industrial environments where electrical noise and surges can be commonplace. Additionally, the device is designed to support multiple nodes on the RS-485 network, accommodating up to 32 devices simultaneously. This versatility allows for expanded networking capabilities, making it easier to integrate multiple devices and sensors into a cohesive communication system.

In terms of configuration, the B&B Electronics 485T is user-friendly, featuring jumper settings that allow for quick adjustments to accommodate different application requirements. Users can easily switch between half-duplex and full-duplex modes, providing greater flexibility based on the needs of their specific communication networks.

The 485T's compact design makes it easy to integrate into existing systems without taking up excessive space, and its durable construction ensures reliability in demanding environments. Furthermore, with a temperature range designed to withstand industrial conditions, the device can function effectively in both warm and cold settings.

In conclusion, the B&B Electronics 485T is a powerful solution for anyone in need of reliable and long-distance RS-232 to RS-485 conversion. With its high data rates, long-distance capabilities, and enhanced durability, the 485T serves as an excellent choice for industrial communication applications, ensuring that devices remain connected and operational even in the most challenging environments.