VBrick Systems EtherneTV MPEG-1, Руководство администратора

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STB Admin Guide 37
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.