Planar WeatherBright LC3251, Product Manual

Page: 22 / 44

LC3251 / LC4751 Product Manual 22
Appendix 1 – RS-232 Serial Interface
RS-232 Serial Interface Introduction
The RS-232 Serial interface allows for remote control and access to overall status of the display. A
series of intuitive ASCII formatted commands are used for bi-directional communication with the
display. This section provides specific information on the RS-232 Serial command format with a table of
fault codes and commands to manage the displays.
RS-232 Interfaces
The display includes two RS-232 interfaces. The primary RS-232 interface allows a remote PC to
control and obtain status of the display. The secondary RS-232 interface provides communication
between the Junction Board and the Video Interface and is internal to the display.
RS-232 Hardware Interface to the Remote PC
This is the external interface to the Remote PC. No handshaking is used. Pin 3 of the DB-9 connector
on the display is data transmitted from the host (Tx); pin 2 is data transmitted from the display and
received by the host (Rx). Baud Rate = 19200, 1 Stop Bit, No Parity.
RS-232 Hardware Interface to the Video Interface Board
This is the internal interface between the Junction Board and the Video Interface Board. No
handshaking is used. Baud Rate = 19200, 1 Stop Bit, No Parity.
RS-232 Serial Communication Formats
This section provides general RS-232 communication format rules and samples of commands to use
when communicating with the LC3251 and LC4751 displays. See the
RS-232 Serial Commands table for
a list of commands.
General Rules

RS-232 commands consist of a string of ASCII characters

All numeric values are decimal; you do not need to use hex or binary digits in the commands

Spaces or tabs may be used in the commands to separate the parts and make them easier for
users to read. This "white space" is ignored by the command reader

You cannot use commas, slashes, or other punctuation as separators. Periods have a special
purpose in commands

Commands are not case sensitive, so you can use upper and lower case letters as you wish

Limited editing of the command is supported – backspace may be used to correct errors in the
command text, but not in the command type

When a command requires a response, wait for the response before sending another command
to another display

All commands must end with a carriage return character, shown as [CR] in the rest of this
document. Depending on your serial communications program, commands may automatically
be ended with a [CR]