VBrick Systems MPEG-1, MPEG-2, MPEG-4 manual Serial Port Passthrough, How Passthrough Works

Chapter 5

Serial Port Passthrough

Overview

Using serial port passthrough, STBs can provide full duplex, end-to-end transparent passthrough of user data from an STB to a VBrick, or to other networked devices. The STB has one serial port that can be used for passthrough. The serial port operates at its configured baud rate (e.g. 300 to 115.2 Kbps). Some common applications include remote control of a camera (pan-tilt-zoom), remote control of security doors, low speed data transport, or data collaboration between PCs. Note that passthrough mode is used to send control information from an STB to/from another device and may not support sustained data at higher data rates.

Topics in this chapter

Overview

How Passthrough Works

Using Telnet

How Passthrough Works

VBrick STBs can receive data on a particular TCP/IP port and transparently output that data to a serial port. Conversely, any data input to a serial port can be passed through to other devices connected to that TCP/IP port. Devices include VBrick appliances or special applications connected to the appropriate TCP/IP port. This feature is called "Serial Port Passthrough." The serial port is assigned port TCP 4439. A typical application is for two VBricks connected to each other's TCP/IP port 4439. In this case, characters typed into a terminal program attached to one VBrick's serial port appear on a terminal program attached to the other VBrick's serial port. In this case, the TCP/IP network serves as an intermediary between the serial ports of two VBrick appliances.

An STB is a Responder of passthrough connections. When configured as a responder it will accept up to 64 connections from initiator appliances. It is possible to Disable Passthrough Mode, so that the STB cannot respond to Passthrough requests. Since the medium used for setting up Passthrough connections is a generic TCP/IP port, any IP device that is prepared to connect to a VBrick's port can be considered as a Passthrough Initiator. The VBrick Responder appliance will not know the exact nature of the device at the other end of the port.

STB Admin Guide 37