Appendix C - Electrical Interface

Appendix C - Electrical Interface

RS-232

Quite possibly the most widely used communication standard is RS-232. This implementation has been defined and revised several times and is often referred to as RS-232 or EIA/TIA-232. The IBM PC computer defined the RS-232 port on a 9 pin D sub connector and subsequently the EIA/TIA approved this implementation as the EIA/TIA-574 standard. This standard is defined as the 9-PositionNon-Synchronous Interface between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange. Both implementations are in wide spread use and will be referred to as RS-232 in this document. RS-232 is capable of operating at data rates up to 20 Kbps at distances less than 50 ft. The absolute maximum data rate may vary due to line conditions and cable lengths. RS-232 is a single ended or unbalanced interface, meaning that a single electrical signal is compared to a common signal (ground) to determine binary logic states. The RS-232 and the EIA/TIA-574 specification define two types of interface circuits, Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE). The OMG-USB-SER-4 is a DTE device.

RS-422

The RS-422 specification defines the electrical characteristics of balanced voltage digital interface circuits. RS-422 is a differential interface that defines voltage levels and driver/receiver electrical specifications. On a differential interface, logic levels are defined by the difference in voltage between a pair of outputs or inputs. In contrast, a single ended interface, for example RS-232, defines the logic levels as the difference in voltage between a single signal and a common ground connection. Differential interfaces are typically more immune to noise or voltage spikes that may occur on the communication lines. Differential interfaces also have greater drive capabilities that allow for longer cable lengths. RS-422 is rated up to 10 Megabits per second and can have cabling 4000 feet long. RS-422 also defines driver and receiver electrical characteristics that will allow 1 driver and up to 32 receivers on the line at once. RS-422 signal levels range from 0 to +5 volts. RS-422 does not define a physical connector.

OMG-USB-SER-4

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Omega OMG-USB-SER-4, Four Port RS-232/422/485 to USB Adaptor manual Appendix C Electrical Interface, RS-422
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Four Port RS-232/422/485 to USB Adaptor, OMG-USB-SER-4 specifications

The Omega OMG-USB-SER-4 is an advanced four-port RS-232/422/485 to USB adapter designed for seamless communication between legacy serial devices and modern computers. This versatile device caters to the growing need for increased connectivity, making it an ideal solution for industrial control, data acquisition, and other applications requiring multiple serial connections.

One of the main features of the OMG-USB-SER-4 is its ability to accommodate various serial communication protocols, including RS-232, RS-422, and RS-485. This flexibility enables users to connect a wide array of devices such as sensors, PLCs, and data loggers without worrying about compatibility issues. Furthermore, the adapter supports full-duplex communication, making it possible to transmit and receive data simultaneously on each port, enhancing overall efficiency.

The OMG-USB-SER-4 is built with robust technology that ensures reliable performance and durability. It supports a data transfer rate of up to 921.6 Kbps, allowing for fast and efficient data handling. Additionally, with its plug-and-play functionality, the device can be easily integrated into existing systems without requiring complex configurations or additional drivers, facilitating a hassle-free installation process.

In terms of characteristics, the OMG-USB-SER-4 features LED indicators for power and activity status, providing users with real-time feedback on the operational state of the device. The unit also includes built-in surge protection, safeguarding connected devices from voltage spikes and electrical noise, which is crucial for maintaining system integrity in industrial settings.

The compact design of the OMG-USB-SER-4 further enhances its appeal, as it allows for easy deployment in space-constrained environments. The device is USB-powered, eliminating the need for an external power supply, making it convenient for mobile or temporary setups.

In conclusion, the Omega OMG-USB-SER-4 four-port RS-232/422/485 to USB adapter combines versatility, speed, and ease of use, making it an excellent choice for professionals looking to bridge the gap between legacy serial devices and modern computing systems. Its robust features, coupled with reliable technology, ensure that it meets the demands of various industrial applications while maintaining user-friendly operation.
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