Daktronics RS-422 Communication - Manual (Page 7)

Introduction
The typical system consists of a Windows based personal computer running Venus 1500
e and one or more displays. In addition, softwar some means of signal connection must be
used to relay signal between the computer and the display. Six network types are available:
RS-232, RS-422, Modem, Fiber Optic, Radio, and Ethernet. Up to 240 displays can exist on
one network.
RS-422 Communication Manual
1
possible ways of connecting signal between displays for
multiple displa
Network C
ce signals.
ot separation is required. The maximum length of an RS-422 signal cable is 4,000
rmination
Serial Port: An actual serial port is required for direct connections from the
computer to the signal converter.
Note: Certain USB adapters create an “actual” serial port and others create
“virtual” ports. The Venus 1500 software will not recognize a virtual port.
Therefore, the use of a USB adaptor is not supported by Daktronics.
The purpose of this manual is to explain those items that are unique to an RS-422
communication system, including the installation and possible servicing requirements. In
addition, the manual will discuss the
y systems.
oncepts
System/Cable Requirements
RS-422 (EIA/TIA-422-B) is a standard communication interface that utilizes a
differential balanced transmission scheme. The main advantage of RS422 is the
longer cable length that is possible. A signal converter is needed to convert the
computer's RS-232 to RS-422.
The cable required for an RS-422 signal is a 4-conductor shielded cable (Daktronics
part number W-1234, Manhattan number M4473). This shielded cable consists of
paired wires. They should not be subjected to mechanical flexing after installation.
This cable is not for direct burial and should have one of the following routings:
• In dedicated, metallic conduit
• Inside buildings – if cable is not in conduit, keep away from
interferen
With interference signals, such as power conductors, intercom, etc., typically a two-
fo
feet (approximately 1.22km) from the signal converter to the signal te
enclosure at the display.
Component Identification
RS-232: RS-232 is a standard PC communication type with a maximum cable length
of 25 feet (approximately 7.6 meters). The signal output of a computer is RS-232,
and when used with an RS-422 system a signal converter is required.
RS-422: RS-422 is a standard differential communication type with a maximum
cable length of 4000 feet (approximately 1.2 kilometers).