GTCO Roll-Up II - Users Guide - Manual (Page 47)

Roll-Up II 47
 Roll-Up II sends a “>” (hex 3E) as a prompt to the commanding device. The Roll-Up II
is now ready to accept commands.
A command consists of two upper case ASCII letters or numbers followed by a delimiter.
The delimiter lets the Roll-Up II know the command is complete. There are two kinds of
delimiters:
 <CR> (carriage return, hex 0D): indicates end of current command and more
commands will follow. If the command just sent is valid, it will be carried out. The
Roll-Up II then sends another > prompt and awaits the next command.
 <ESC> (escape, hex 1B): indicates end of current command and no more commands
will follow. If the command is valid, it will be carried out. Then the Roll-Up II will exit
Command Mode and return to Digitizing Mode.
If you are entering several commands, end each one with a carriage return delimiter. After
each <CR>, the Roll-Up II carries out the command and sends a new command prompt.
After the last command or if you are entering only one command, use an <ESC>. The
Escape delimiter takes you directly back to Digitizing Mode.
If the command entered is not recognized as a valid command, it will be ignored and Roll-
Up II will send a “?” (question mark). If the delimiter following an invalid command was an
<ESC> (indicating your desire to leave Command Mode), Roll-Up II stays in the Command
Mode, awaiting a valid command.
A command may be aborted before entering a delimiter by sending a CTRL-X (hex 18). The
Roll-Up II then ignores the preceding one or two characters and responds with a new
prompt.
To Leave Command Mode:
Send an <ESC> (hex 1B). The <ESC> may follow a command code or it can be sent in
response to the Roll-Up II’s prompt. Roll-Up II returns to digitizing, now operating
according to the commands sent to it.
A Hint for Programmers
Here is the most efficient method for sending commands:
1. Send the CTRL-A and wait until the Controller responds with the prompt >. A loop
that retrieves one byte at a time from the serial port and checks for the > is best.