Maple Systems MAP450D - Manual (Page 29)

APPENDIX A
Control Commands
Control commands are multiple ASCII characters, starting with the command initiator (ESC
control character) and ending with the command terminator (STX control character) or line
terminator. These commands allow the host controller to request and send information to the
OIT. Control commands are always sent by the host controller to the OIT.
The first letter after the command initiator is the command letter. The command letter
determines which action the OIT performs. Following is any necessary or optional
command data. The command data is always in ASCII format, meaning that all command
data must be printable ASCII characters.
The following rules must be adhered to when the host controller sends a control command:
• Each control command must begin with the command initiator (ESC control character).
• Each control command must end with either the command terminator (STX control
character) or line terminator.
• Except for the command initiator, the command terminator, and the line terminator, all
other characters sent by the host controller must be printable ASCII characters.
If the control command requires a response from the OIT, the OIT immediately responds
with any requested data and the line terminator.
Terminators
There are two types of terminators used in control commands: the command terminator
and the line terminator. The command terminator is the STX control character and is
used to indicate the end of a control command. The line terminator is programmable and
can be CR, LF, CR/LF, or ETX. The line terminator is used by the host controller to
indicate the end of a control command or to “log off” an OIT when operating in Network
mode (refer to Chapter 2: Operating Modes).
Notation Conventions
This section uses the following type styles to define control command syntax:
SMALL CAPS
Used for non-printable ASCII control characters. Control characters
are sent to the OIT using decimal or hexadecimal notation or by
sending a BASIC CHR$ command. The control characters can also be
generated from the keyboard of a computer when using a terminal
emulation program. The table, below, lists the control characters
recognized by the OIT when sent by the host controller.
bold Used for literal portions of the syntax that must be used exactly as
shown (including upper/lower case).
italics Used for variables that specify the type of data to include.
Note: Spaces are shown between the segments of the control command for clarity only.
Spaces should not actually be sent. For example,
ESC
A text terminator should be sent as
ESC
Atextterminator.
Appendix A: Control Commands 28
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