Dynapro Technologies Dynapro ET TCS, Application Developer'S Manual

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5-30
When a character font is mapped into a character set, it is as if the contents of the character set
have been temporarily replaced with those of the character font. However, it is more than just a
copy operation because subsequent changes to the character font are immediately reflected in the
character set. Since the Standard and Extended Character Sets are used by the TCS to translate
incoming graphic codes into displayable characters, changes to a character font that is mapped
into a character set by the Displayed Screen have immediate visual effect. Changes to a character
font that is mapped into a character set by a stored screen have no visual effect until the stored
screen becomes visible by being copied into the Displayed Screen.
Unless the host uses this command to change the default character font mapping, the Static
ASCII and Static Special Character Fonts will be mapped into the Standard and Extended
Character Sets, respectively, by every screen.
Character positions within each character font are numbered from 1 through 128 (decimal);
communications codes that access the Standard Character Set range from 0 through 127
(decimal); and those which access the Extended Character Set range from 128 through 255
(decimal). Programmers should use care when determining the code value that must be sent to
access a given character. Table 5-4 shows the necessary relationships between a character’s
position in the font and its corresponding communication code once the character font has been
mapped into a character set.
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Before mapping a dynamic character font into either of the character sets, the programmer should
become familiar with the default characters in the Standard and Extended character set that have
special use within the TCS. Table 5-5 and Table 5-6 indicate the consequences of replacing
certain default characters within the Standard and Extended Character Sets with custom
characters when a dynamic character font is mapped into one of the character sets. It is
recommended that characters in these locations not be changed from their default values except
with care.