VIEWSONIC CD4220 - Manual (Page 47)

3.
Introduction
This document describes the hardware interface spec and software protocols of RS232 interface
communication between Viewsonic Commercial Display and PC or other control unit with RS232
protocol.
Viewsonic CD4620 and CD4220 contain with 2 set of protocol command
1.
Protocol 1, with ID
This set protocol allow user to assign the ID in the command to control the specify ID monitor
2.
Protocol 2, without ID
The set protocol is best for single display control and for Viewsonic NMP-530.
Both sets protocol contain three sections command:
z Set-Function
z Get-Function
z Remote control pass-through mode
※ In below document, “PC” will represents all the control units that can sent or receive the RS232
protocol command.
4.
Description
4.1 Hardware specification
Viewsonic LCD communication port in the rear side
(1) Connector type: DSUB 9 Pin Male
(2) Pin Assignment
Male DSUB 9Pin
(outside view)
Pin # Signal Remark
1 NC
2 RXD Input to LCD Monitor
3 TXD Output from LCD Monitor
4 NC
5 GND
6 NC
7 NC
8 NC
9 NC
frame GND
*Use of crossover (null modem) cable
required for use with PC
4.2 Communication Setting
- Baud Rate Select: 9600bps (fixed)
- Data bits: 8bits (fixed)
- Parity: None (fixed)
- Stop Bits: 1(fixed)
4.3 Command Message Reference
PC sends to Monitor command packet followed by “CR”.
Every time PC sends control command to the
Monitor, the Monitor shall response as follows:
1. If the message is receives correctly it will send “+” (02Bh) followed by “CR” (00Dh)
2. If the message is receives incorrectly it will send “-” (02Dh) followed by “CR” (00Dh)
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