Manual

Escape Sequences 6-1
6 Escape Sequences
The Automove System recognizes a number of escape sequences to establish
communications parameters and to request that various information be sent back to the host.
The escape sequences do not go into the input buffer; instead, they are acted on immediately
as they are received.
Each sequence consists of at least three ASCII characters: Escape (
ESC, character code 27
decimal), period (character code 46 decimal), and one of the characters @, !, ), (, B, E, H, I,
J, K, L, M, N, O, R, S, Y, or Z. These letters must be uppercase. In addition, some
sequences allow one or more numeric parameters, separated by semicolons ";" and
terminated by a colon ":". If no digit characters precede a semicolon or colon, the
corresponding parameter receives a default value.
No semicolon precedes the first parameter. When a colon is received, any parameters which
have not been specified are defaulted. If a particular escape sequence does not allow
parameters, no colon is allowed after the sequence. Conversely, if a sequence allows any
parameters, even if they are all to be defaulted, a colon must be sent.
If a parameter is to be defaulted but a following parameter is to be specified, a semicolon
must be sent as a "placeholder" for the defaulted parameter.
There are three types of parameters:
A DEC parameter can be in the range 0 through 65535; larger numbers are interpreted as
65535. Some DEC parameters have other restrictions, which are explicitly noted below.
An ASC parameter is a numeric representation of a single ASCII character; it can be in the
range 0 through 127. (For example, the value 13 represents the Carriage Return character
and 88 represents the letter "X".) Numbers greater than 127 cause an error to be logged.
A STR parameter represents a string of ASCII characters; it may consist of up to 10 ASC
values separated by semicolons. A colon, a defaulted value, or a value of zero anywhere in a
STR parameter terminates the string; the zero does not become part of the string, and
subsequent values are ignored. The STR parameter is set to the null string (i.e. no string) if
no ASC parameters precede the colon, or if the first ASC value is zero or is defaulted.
No ASCII spaces, control characters, or other extraneous characters are allowed within the
escape sequence; the only allowable characters are the Escape itself, the period, the digits 0
through 9, semicolon, and colon.
When an escape sequence (or an OS, OE, etc.) requests output from the Automove System,
the System sends the requested information in ASCII, then sends an Output Terminator
sequence. The Output Terminator defaults at power up to be a Carriage Return followed by
a Linefeed. It can be changed via the
ESC.M command to be any sequence of zero, one, or
two characters. (Zero would not be very useful, since the host would not know when to
terminate the last numeric value.)