Introduction; Supported Serial Protocols - Black Box 16-Port Rackmount 10/100 Installation Manual

1: Introduction

The Black Box LES2700A-16-R3 and LES2700A-32-R3 are Terminal Servers that
provide shared network access to terminals, devices, console ports, and printers for a
variety of network protocols and operating systems. These Terminal Servers support the
TCP/IP, IPX (NetWare), Local Area Transport (LAT), AppleTalk (EtherTalk), and
Microsoft LAN Manager protocols.
The Terminal Server stores its executable software in Flash (rewritable) ROM, meaning
that it does not have to download software from a host each time it boots. Software must
only be downloaded when a new software version becomes available. See Appendix 13
for more information.

1.1 Supported Serial Protocols

All Terminal Server models support the RS-232/423 serial protocol.
1.1.1 RS-232
The RS-232 line interface standard is a single-ended peer-to-peer interface. Today's
personal computers typically have at least one RS-232 serial port. It is the most common
serial protocol used today.
RS-232 is used for connecting devices across short distances at speeds up to 230.4 kb/s.
Faster speeds require shorter cabling to ensure error-free communication. The maximum
cable length at a given speed is determined by many factors, including the immediate
electrical environment and the quality of cable used, but is usually less than 15 meters at
high speeds.
1.1.2 RS-423
All of the Terminal Server models support the RS-423 line interface standard. RS-423
devices are interoperable with RS-232 devices. That is, RS-232 ports can receive data
reliably from RS-423 ports and vice-versa.
The main difference between RS-423 and RS-232 is that RS-423 employs lower voltage
signaling and differential receivers. RS-423 still uses single-ended transmitters for
compatibility with RS-232 receivers.
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