Lantronix ETS Reference Manual - 2: Concepts
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2: Concepts
The ETS provides two major functions: outgoing sessions, which are basically interactive connections to
other nodes, and incoming connections to services, such as printer and modem support.
2.1 Services
Services are the basic method of connecting to the ETS from any host or another server. In general, a service
is required on the ETS before any job or connection queueing will take place. See the Server Configuration
chapter for details on creating and using services.
2.2 Serial Protocols
The ETS models support RS-423 and RS-422 serial protocols. In addition, they are compatible with RS-232
devices.
2.2.1 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 communications. 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 10 meters at high speeds.
Lantronix MSS models have RS-232 ports. RS-232 devices are interoperable with RS-423 devices.
2.2.2 RS-423
All of the ETS 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.
RS-423 is generally rated at higher speeds over longer cabling runs than RS-232. Maximum data rates of
230.4 kb/s are possible on ETS-PR models, and 115.2 kb/s is the maximum on ETS-P models.