Contemporary Research QMOD-HD Manual - Manual (Page 10)

Contemporary Research 10 QMOD-HD
RS-232 Control Protocol
Overview
The QMOD-HD full duplex RS-232 enables a system programmer to control all functions as well as monitor
status. All commands are sent as ASCII strings. No delays between characters or commands are required, as
data is interrupt driven and buffered.
One QMOD-HD may be daisy-chained together with a CR 232-series tuner from a single RS-232 port. The
QMOD-HD is pre-set to Unit 1, and the tuner would be set to Unit 2.
Communications parameters (Front Panel Mode 1) are 300 to 19200 baud, 8 data bits, No parity, and 1 stop
bit. Factory default is 9600 baud, Unit#1.
All settings are saved to NVRAM in the QMOD-HD.
The QMOD will accept non-standard RS-232 control such as voltage that swings from 0 to +5 VDC,
commonly found when IR ports are used to send RS-232 commands.
General protocol specifications
Characters in command strings to the QMOD-HD are common ASCII keyboard characters.
Command strings sent to the QMOD-HD begin with the ASCII > (greater than symbol) as an 'Attention'
character and end with carriage return - ASCII CR, Hex $0D, or keyboard Enter - as an 'End-of-command'
character.
Responses from the QMOD-HD begin with the ASCII < (less than symbol) as an 'Attention' character and
end with a carriage return followed by line feed an ASCII LF or Hex $0A as 'End-of-command' characters.
A carriage return is required at the end of each command and is assumed in all examples.
Command String Structure
[Attention] (Unit#) [Command] (Parameters) [Return]
Attention
Single character (>) starts the string
Unit# The Unit# is expressed as an ASCII 0-9 when used in multiple tuner applications.
To address all units, use a Unit # of 0 (Zero)
No unit number will default to Unit#1
Command A two-character command
Parameters Added attributes to some commands
Return A carriage return ends the command string, you may use ASCII CR, Hex $0D, or keyboard
‘Enter’ in programming. For simplicity, the programming examples in the manual will not
show the ‘CR’ – so remember, you’ll need to add it in your control code.
Command and Status Response
Commands can be sent back to back at any time without any delay. To allow for rapid, multiple commands,
status responses are intentionally delayed by about 125mS, sending the most current status in response to
control commands or user actions.