Dynapro Technologies Dynapro ET TCS, Application Developer'S Manual

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3-11
2. Command Lookup
The TCS looks up a command using the combination of the control sequence’s private
command code, the Final code, and possibly the first parameter. The TCS does not have a
command for every possible control sequence combination. If the TCS has a corresponding
command, the TCS accepts the parameters and performs the command. If the TCS does not
have a corresponding command, the TCS ignores the control sequence.
For example, the sequence
<ESC>[12;5F
is in the correct format, and can be parsed by the TCS. However, when it is looked up, no
corresponding command is found. Therefore, the sequence is ignored by the TCS.
The parsing step assumes that all parameters are omitted from the command. If a parameter is
found, its value is stored with the control sequence. When the command is executed, the list of
parameters is provided. If more parameters are specified in the sequence than expected for the
command, the TCS ignores the additional parameters. If fewer parameters are specified than
expected, the omitted parameters assume default values.
&DQFHOLQJ&RQWURO6WULQJV
A control string can be canceled before the entire string is sent by sending either a <CAN> or
<SUB> code to the TCS. Either code causes the TCS to ignore all previously received codes up
to and including the previous <ESC> or <CSI> code.
(UURUVLQ&RQWURO6WULQJV
Generally, the codes <SP> through ~ (32 through 7E hex) are valid within control strings. Codes
within this range do not cause a control string to be aborted, even if the TCS does not recognize
the resulting control string. Codes outside this range cause the interpretation of the control string
to be aborted immediately. The portion of the control string received prior to the invalid code is
ignored and re-interpretation of the input begins with the invalid code. If the invalid code is a
graphic code (representing a character in the Extended Character Set), it will be displayed. If the
invalid code is a control code, it will be interpreted normally.
Under certain conditions, some control codes do not cause the interpretation of a control string to
be aborted. Table 3-3 lists these control codes and the conditions under which they can be
received within a control string without affecting interpretation of the string. Note that if the
stated conditions for a code are not met, the code aborts interpretation of any control string
within which it is found.