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Virtual Key Names
464 TeemTalk Virtual Key Name Functions
Reading Text From
a File or Device
The following command format is used to read a string from a file or
device (e.g. COM1) and push it into the keyboard buffer as if typed.
This can be used, for example, to trigger a bar code reader, read back
the code and enter it as if typed at the keyboard.
<VK_FILE_I><name>max length,retries,termination
char<VK_FEND>
where:
name
is either the name of the file or the name of the device to be
read from.
max length
specifies the maximum number of characters to be
read before terminating. Entering
0
will give a default of 512 char-
acters.
retries
specifies the number of 100ms retries before terminating.
Entering
0
or 999 is taken as no time out (wait forever). A negative
value prevents keyboard intervention and the value is made positive.
termination char
is the decimal value of the ASCII character
used to terminate the command. Entering
0
will give a default of 26
(EOF).
A read can be terminated by the following four conditions:
•
the maximum number of characters being read,
•
the termination character being read (this is inhibited by a
0
value),
•
the number of specified retries has been reached (this is inhibited
by a
0
or
999
value),
•
the user presses a key (this is inhibited by a negative timeout).
For example, the following command will read up to 20 characters,
end at the first CR (carriage return) character, never timeout but
allow a key press to cancel the read:
<VK_FILE_I><com1:>20,0,13<VK_FEND>