IAI America XSEL-QX - Manual (Page 439)

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Appendix
(4) Program
[1] String process commands
A “string” refers to a series of characters. This controller supports global strings and local strings.
Global strings can be read or written commonly from any program, while local strings are effective
only within a given program and cannot be used in other programs. Numbers in different ranges are
assigned to global strings and local strings, respectively:
Global areas
300 to 999 (700)
Local areas 1 to 229 (229)
String commands are needed because normally controllers communicate with external devices by
means of serial communication, and serial communication data must be processed as strings. This
controller supports serial communication. In operations performed via serial communication, strings
may have to be compared against each other, moved, or converted. This controller provides a set of
commands to do all these.
[2] Explanation of transmission format
Communication by this system is basically implemented through exchange of strings.
Rules about these strings are set beforehand, such has which strings are used in which operations,
so that the receiving side can recognize each string and perform a corresponding operation.
A combination of these strings, and characters indicating the end of a string, is called a
“Transmission Format.” The user can define desired transmission formats freely.
For example, let’s say a 4-character string “HOME” is defined as a command to perform home return.
This string is followed by a character indicating the end of a string. In theory, any character can be
used to serve this role. In reality, however, “CR” and “LF” must be used according to the definitions
used by the PC.
Example of transmission format
String indicating a home
return command Character indicating
the end of a string