Serial Hubs

Serial hubs allow the transparent connectivity of serial devices such as industrial instruments, point-of-sale (POS) terminals, and barcode printers with local area networks (LANs) and wide area networks (WANs). The hub plugs into a USB port on the computer and provides four or more USB ports for peripherals. The peripherals themselves may also contain hubs. For example, a monitor may have a built-in USB hub in order to provide a convenient desktop location for plugging in other devices. USB hubs are available with either 4 ports or 7 ports. To connect serial devices to a USB port on a PC, a USB to serial connection is needed, which can be established using USB serial adapters. Serial hubs support many different serial communication protocols. Examples include an RS232, RS422 and RS485. A user can connect hubs in serial to expand a network and provide easy connectivity for plugging in other devices. A serial port server enables adding serial ports to a system. It transfers data between a computer’s serial port (COM port) and an Ethernet local area network (LAN). Serial hubs are used by applications to access network-based serial devices as if they are locally attached.

There are several ways in which serial hubs function. A serial hub enables the placement of serial COM/TTY ports at the point of need, anywhere on a local or remote LAN segment. Ports on a hub can be assigned to different hosts. A serial hub works together with PC-based drivers that capture COM/TTY port requests and redirect those requests to serial peripherals across the network. Serial hubs enable peripheral sharing and can also manage and monitor network. Serial hubs enable access to local or remote serial devices through standard TCP/IP networks easily and in a cost effective manner. Serial hubs provide dual host connectivity. Serial hub based ports can connect multipule computers with different operating systems. For example computers having operations systems such as Windows NT, Windows 2000, Linux, and Unixware can connect to the same serial hub simultaneously. Some of the technical specifications of serial hubs include power, serial connector, modem control, OS support, speed, and surge protection. Serial hubs are designed and manufactured to meet most industry specifications.

Serial hubs can be used in many different applications. Serial hubs can be designed for versatile support of applications in industrial automation, process control, manufacturing, and across a broad range of commercial operations including retail POS, hospitality, back office, medical, and security systems. An Ethernet serial port server is an ideal connectivity solution for terminals, modems, printers, PCs, and many other serial devices. Standards have been developed to insure compatibility between units provided by different manufacturers, and to allow for reasonable success in transferring data over specified distances and/or data rates. Serial hubs should adhere to Electronic Industries Association (EIA) standards for RS232, RS422 and RS485 for data communication.

• Protecting the Universal Serial Bus from Over Voltage and Overcurrent Threats
  This application note addresses the various requirements for protecting the Universal Serial Bus (USB) from overcurrent and over voltage environmental threats.The solutions presented cover both USB...
  (read more)
• USB Embedded Host Stack
  AN1140 USB Embedded Host Stack Most USB peripheral devices are divided into Author: Kim Otten categories, called classes. Each class has special Microchip Technology Inc. requirements regarding its...
  (read more)
• USB Embedded Host Stack Programmer's Guide
  AN1141 USB Embedded Host Stack Programmer's Guide FEATURES Author: Bud Caldwell Microchip Technology Inc. * Supports USB embedded host applications * Handles device enumeration and configuration *...
  (read more)

Pages: 1 - 3 of 162