Dynapro Technologies Dynapro ET TCS, Application Developer'S Manual

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Because only half of the control codes can be sent using 7-bit codes, ANSI created a mechanism
to allow each 8-bit control code to be specified by an equivalent 7-bit escape sequence as shown
in Table 3-2. This allows full access to all control codes, regardless of whether the TCS and host
are communicating using 7- or 8-bit codes. Because the TCS ignores many of the 8-bit control
codes, Table 3-2 shows only those 7-bit sequences corresponding to the 8-bit control codes acted
on by the TCS.
Although each character set contains characters in locations that correspond to control codes,
these characters cannot be directly displayed. This is because the corresponding communication
code will be interpreted as a control code since it falls within the range of control codes defined
by ANSI. The characters in these locations are generally used for special purposes and can only
be displayed indirectly by:
•
Operation within the Communication Monitor
•
Region commands that specify a boxtype
•
Region commands that specify custom characters
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Of the 256 communication codes, those that are not reserved for use as control codes are graphic
codes. Each graphic code specifies a location within either the Standard or Extended Character
Set of a character that is to be displayed.
Characters within the Standard Character Set can be displayed by sending the appropriate 7- or
8-bit graphic code. Characters within the Extended Character Set can be displayed either by
sending the appropriate 8-bit graphic code, or by selecting the Extended Character Set (using the
Select Character Set command) and sending the proper 7-bit code.
Graphic codes always cause a corresponding character to be displayed on a screen except when
they are embedded within a control string as described under Control Strings further on in this
chapter.