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7K • Chapter 4
Control Characters
Control Characters are small code groups which you place into a message to
give instructions to the message handler. The message handler recognizes
control characters because they always begin with 99.
When the message handler encounters a group of characters which begin with
99, it looks at the digits immediately following the 99 for the instructions. It then
performs the desired action.
Since none of the libraries (CW, beeps, synthesized speech, etc.) have
characters beginning with 99, the message handler won't confuse library
characters with control characters. (Don't be concerned if you program a tone
page or a custom code group that happens to contain a 99 sequence in the
data. Since the character group doesn't begin with 99, it will be interpreted
correctly.
Note: Don't confuse the 99 being discussed with the password (PW) used to
enter commands, which happens to default to 99. control characters are used
only within messages. You can change the password, but you cannot change
the control characters. They must always begin with 99.
Any message that you program into the controller can contain one or more
control characters. Control characters can occur anywhere in the message
depending on how you want the message to be sent. Of course, you will need
the Speech Synthesis Module option if you want to send a speech message,
and you'll need a Telephone Interface Module option if you want to send a
message to the phone line.
It's a good idea to begin every message you program with two control
characters: One defines the type of message you want to send. The other
selects the routing (audio path). If you don't specify the message type, the
controller will assume you want to send a CW message. If you don't specify the
routing, the controller will assume the message goes to transmitter #1, unless
the phone line is engaged in control mode. In that case, all messages go to the
phone line. Since many of your messages won't fit these conditions, get into
the habit of specifying your choices with control characters.
The message handler executes control characters as it finds them in the
message. It does not "look ahead" to see if you will be changing any conditions.
Therefore, you must enter the control character ahead of the desired message.
We list the possible control characters next, then show some examples of their
use.
4-2
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