6. External Control
In addition to using the display keypad or remote control unit, you can control the display using a serial (RS-232) link to
send ASCII commands and receive responses to those commands.
You also use discrete infrared (IR) control codes to program a third-party remote control unit. For more information, refer
to Using Discrete IR Codes on page 46.
Serial Communications
The display uses a simple text-based control protocol to take requests from control devices and to provide responses
to such devices. This section describes how to send control messages over a serial link between the display and an
automation/control system or a PC running a terminal emulation program such as Windows® HyperTerminal or Tera
Term.
RS-232 Connection and Port Configuration
Connect your control system or PC to the RS-232 input of the display as shown in Figure 3-2.
Configure the RS-232 controller or PC serial port as follows: no parity, 8 data bits, 1 stop bit and no flow control. Set the
baud rate to 115200, to match that of the display RS-232 port.
Command and Response Format
Commands sent from an automation/control system or PC to the display must have the following
format: [STX] [IDT] [TYPE] [CMD] ([VALUE] or [REPLY]) [ETX] [CR]
Where:
•
[STX] indicates the start of the command data (always 07).
•
[IDT] is the display ID (always 01).
•
[TYPE] is the command type:
00 = return to host (response from the LCD panel)
= read / action
= write
•
[VALUE] is the parameter setting for the command.
•
[REPLY] is the parameter setting for the command, acknowledged by the display in its response to a command.
•
[ETX] indicates the end of the command data (always 08).
•
[CR] is the ASCII carriage return key (0x0D).
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