1.3 Network
Concepts
The concept of using LED displays as a cost effective, high impact method of
communication is rapidly growing throughout many industries and businesses. The
reasons for this growth are many, but the need for additional features and the
complexity of multiple sign installations has emerged. Daktronics display systems
have been designed to meet those needs. The common thread to most client requests
is a means of programming and controlling a group of signs from a central control
point. Daktronics responded by developing a power system of interconnecting and
controlling signs. Great care has been taken to design products that will satisfy a wide
variety of installations. Some of the design goals of these systems include the
following:
·
Easy transfer of messages
·
The ability to tell a sign or group of signs in the network which message
should run
·
The ability to determine the status of any sign on the network
·
The ability to control multiple sign technologies on the same network
All the programming features would seem insignificant if the systems could not be
accomplished with basic tools and without technical difficulty. Daktronics decided to
use the very popular and readily available RJ11 connector. This connector is also
used on modern home and office telephone equipment.
All that is required for signal installation is standard six (6)-conductor modular
telephone wire and a tool to install the connector. Tools required for mounting the
display depend on the location and size of the display. For some installations, it may
be possible to purchase pre-terminated telephone cables for use with the displays.
There are four (4) network systems available: RS232, RS422, modem, and fiber
optic.
RS232 Network
RS232 (EIA/TIA-232-E) is a standard communication interface that employs a
single-ended serial transmission scheme that uses a maximum cable length of 8
meters (25 feet). This interface was designed for computer communication at short
distances. All computers have an RS232 communications port. Refer to
Section 3
for
additional information.
RS422 Network
RS422 (EIA/TIA-422-B) is a standard communication interface that utilizes a
differential balanced transmission scheme, which uses a typical maximum cable
length of 1.2 km (approximately 4,000 feet). The main advantage of RS422 over
RS232 is the longer cable length that is possible. A signal converter is needed to
convert the computer’s RS232 to RS422. Refer to
Section 3
for additional
information.
Introduction
1-3
