HDG-4000 ANALOG/DIGITAL VIDEO CALIBRATION GENERATOR SERIAL INTERFACE MANUAL
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Serial Protocol
The USB port emulates an RS-232 connection, so the computer (controller) must
be set to the proper Com Port protocols when using the RJ-12 RS-232 port or the
USB port. The controller (computer) should be set to 8 bits, no parity, and 1 stop
bit. It must also be set to match the HDG-4000 baud rate, which can be selected
from 9600 baud to 230.4K baud in the OSD menu. Xon/Xoff flow control, or no
flow control for the RS-232 port can be selected in the OSD menu, and DTS/RTS,
Xon/Xoff, or no flow control can be selected for the USB port.
Note: It is often easier to start with a slow baud rate (e.g. 19200 baud) and no flow
control when initially setting up a connection. The high baud rates of the HDG-
4000 are primarily for use when adding new features through firmware updates.
Slower baud rates (e.g. 19200 or 9600 baud) are perfectly adequate in normal
use, and will permit very long connections (50-100 ft or more) over inexpensive 4-
wire telephone cables.
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HDG-3000 Compatibility
Programs previously written for the HDG-3000 Video Generator may only support
9600 baud, which was the only baud rate available in the HDG-3000.
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HDG-4000 Command Syntax
The HDG-4000 accepts ASCII text commands. Each command is 2 to 12
characters in length and must be followed by a carriage return (CR) character
(ASCII 13). You may not send multiple commands with a single CR. Partial
command strings are not valid.
Capital and non-capital characters are accepted, i.e. a = A, B= b.
All spaces and line feed (LF) characters are ignored.
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Confirmation and Error Messages
The HDG-4000 will return “OK” (without quotes), followed by CRLF (ASCII 13,
ASCII 10), after executing each valid serial interface command.
If the HDG-4000 receives an unrecognized character string of 12 characters or
less it will return “ER “ followed by the unrecognized character string, followed by
CRLF. If more than 12 characters are received only the first 12 chars are returned
in the error message, and the remaining characters are discarded.
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Query Commands
Query commands end with a question mark (?). Query commands return one or
more text strings (each 14 characters maximum), each followed by a CRLF. “OK”
followed by CRLF will be returned after the last text string.
To avoid a possible buffer overrun when sending multiple Query commands, wait
for the “OK” response before sending the next Query command.
Serial Protocol
Serial Command
Syntax
“OK” Message
“ER “ Message
Query
Commands
