Black Box AC216A, User Manual

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Chapter 8 : PROGRAMMER'S GUIDE Multi-Input Video Scaler
PAGE 18
Chapter 8 : PROGRAMMER'S GUIDE
8-1. INTRODUCTION
If you need to use your own Software Control program with a PC or WORKSTATION via an RS-232 port, the Multi-
Input Video Scaler allows communication through an ASCII code protocol.
The Multi-Input Video Scaler treats any character that it receives on the RS-232 as a possible command but it only
accepts legal commands. There is no starting/ending code needed in a command string.
A command can be a single character typed on a keyboard and does not require any special character before or after it. (It is
not necessary to press "ENTER" on the keyboard). A command can be preceded by a value. (See chapter 8-2
COMMANDS STRUCTURE ).
When the Multi-Input Video Scaler receives a valid command, it will execute the command. Then the Multi-Input Video
Scaler will send back the status of all the parameters that have changed due to this command.
If the command cannot be executed (value out of range, no signal on the selected input), the Multi-Input Video Scaler will
just send back the current status of the corresponding parameters.
If the command is invalid, an error response will be returned to the controlling device. All responses returned to the
controlling device end with a carriage return <CR> and a line feed<LF> signaling the end of the response character string
(See chapter 8-3 ERROR RESPONSES)
8-2. COMMANDS STRUCTURE
Commands are usually composed of a numerical value followed by the command character. The characters used without
any numerical value return the current setting of the command.
COMMAND structure = VALUE (optional) + CHARACTER.
Examples:
COMMAND
VALUE CHARACTER
RESPONSE DESCRIPTION
none H HPOS15 Read Horizontal position.
10 V VPOS10 Set Vertical position to 10.
8-3. ERROR RESPONSES
When the Multi-Input Video Scaler receives from the controlling device an invalid command or value, it returns an
error response:
COMMAND
VALUE CHARACTER(S)
RESPONSE DESCRIPTION
none Z E10 Invalid command.
70260 V E13 Invalid value.