EX II Controller Communications
19
3M Touch Systems Proprietary Information
The
terminator
is the last character of each command string and is an ASCII carriage
return CR. An ASCII CR control character is 0D hexadecimal. To enter a carriage return,
ending the command sequence, use Enter or the key combination Ctrl M (^M).
This chapter lists each command as a string of ASCII control characters and printable
characters consisting of a header, the command, and a terminator as follows:
<SOH>
Command
<CR>
Receiving Responses from the Controller
After executing a command, the controller returns a response or acknowledgment to the
host system. Each controller response consists of a header, the command response, and a
terminator in the following format:
<Header>Command Response<Terminator>
Note:
The following descriptions of header, response, and terminator, use 3M Touch
Systems terminal emulator key sequences. The format of controller responses varies
depending on the terminal emulation mode you are using.
The
header
is the first character in the response string and is the ASCII start-of-header
control character SOH. The hexadecimal code for the ASCII SOH control character is 01.
If you are working with an IBM PC compatible system in terminal mode, the SOH
control character returns a
☺
character to the screen.
The
response
, which always follows the header, is a range of ASCII characters depending
on the type of command sent. Responses can be in many forms. For example, one
standard response is
0
(ASCII character ‘zero’ or 30 hexadecimal). This response
indicates a successful command completion for most commands, while it indicates a
failed completion for other commands. See the firmware reference section for a
description of what the response indicates for
each
particular command.
Another standard response is
1
(ASCII character ‘one’ or 31 hexadecimal). In most cases,
this response indicates the command failed. The controller received an invalid command
that it could not execute.
Some possible reasons for a command failure include:
•
The command was not formatted correctly.
•
The system parameters were not set up to allow command execution.
•
The controller does not support the command.
The
terminator
is the last character of each response string and is an ASCII carriage
return CR. The hexadecimal code for the ASCII CR control character is 0D hexadecimal.
The value returned in the response will be the ASCII control character for a carriage
return, displayed on the screen as the cursor moving to the next line.
