RS-422/485 SERIAL INTERFACE PLUS, 4-PORT

3.5 RS-485 Enable Modes

RS-485 is ideal for multi-drop or network environments. RS-485 requires a tri- state driver (not dual-state) that will allow the electrical presence of the driver to be removed from the line. The driver is in a tri-state or high-impedance condition when this occurs. Only one driver may be active at a time and the other driver(s) must be tri-stated. The output modem control signal Request To Send (RTS) is typically used to control the state of the driver. Some communication software packages refer to RS-485 as RTS enable or RTS block-mode transfer.

One of the unique features of the Serial Interface Plus Card is the ability to be RS-485 compatible without the need for special software or drivers. This ability is especially useful in Windows, Windows NT, and OS/2 environments where the lower-level I/O control is abstracted from the application program. This ability means that you can effectively use the Card in an RS-485 application with existing standard RS-232 software drivers.

Headers J1D through J4D are used to control the RS-485 mode functions for the driver circuit. The selections are “RTS” enable (silk-screen “RT”) or “Auto” enable (silk-screen “AE”). The “Auto” enable feature automatically enables/disables the RS-485 interface. The “RTS” mode uses the “RTS” modem control signal to enable the RS-485 interface and provides backward compatibility with existing software products.

Position 3 (silk-screen “NE”) of J1D through J4D is used to control the RS- 485 enable/disable functions for the receiver circuit and determine the state of the RS-422/485 driver. The RS-485 “Echo” is the result of connecting the receiver inputs to the transmitter outputs. Every time a character is transmitted, it is also received. This can be beneficial if the software can handle echoing using received characters to throttle the transmitter or it can confuse the system if the software does not. To select the “No Echo” mode select silk-screen position “NE.”

For RS-422/530/449 compatibility, remove the jumpers at J1D through J4D.

Examples on the following pages describe all of the valid settings for J1D-J4D.

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Black Box RS-422, IC183C manual RS-485 Enable Modes
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IC183C, RS-422, RS-485 specifications

The Black Box IC113C and IC175C are part of a series of versatile RS-485 interface converters designed to facilitate reliable data transmission over long distances. RS-485 is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems, and these specific Black Box converters exemplify the technology's adaptability and robustness.

The IC113C is an RS-485 to RS-232 converter, providing a seamless transition between these two common serial communication protocols. With a compact design, it boasts an operating temperature range of -40 to 85 degrees Celsius, making it suitable for harsh environmental conditions. Its key feature includes the ability to extend the communication distance up to 4,000 feet, which is ideal for industrial applications where devices may be far apart. Additionally, the IC113C includes built-in surge protection, ensuring that the device can withstand electrical noise and spikes, ultimately increasing the system's reliability.

On the other hand, the Black Box IC175C serves as an RS-485 to USB converter, bridging older serial devices with modern USB interfaces. This converter is critical for users wanting to connect legacy equipment to contemporary computing systems. Featuring a plug-and-play design, the IC175C is easy to install with no external power supply required, as it is powered directly through the USB connection. It also supports data rates up to 115.2 Kbps, ensuring fast and efficient data transfer.

Both models employ differential signaling, which enhances noise immunity and allows for greater transmission distances compared to single-ended communication standards. Furthermore, the converters support multiple nodes on the same bus, accommodating a network of devices without requiring complex wiring schemes.

In summary, the Black Box IC113C and IC175C offer essential features that cater to diverse industrial and commercial applications. With their robust construction, extensive operating ranges, and compatibility with various communication protocols, these converters enhance system interoperability and provide durable solutions for long-distance data communication needs. Whether connecting legacy systems or extending communication capabilities, these devices exemplify reliability and efficiency in modern data transmission technologies.
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