Four Character Command String

To turn any selected port off, the first and second character of the command control string must be the user-defined character. The third character must be the ASCII EOT character (decimal 4).

Example 2: To turn off all ports, with ASCII STX (decimal 2) set as the user defined character.

Send to the Master Port: STX STX EOT (2 2 4 decimal)

It is recommended that the user-defined character be a non- printable character. The turn off command will then consist of three characters that will not show up on the current port device.

If you were writing a program in GWBASIC to select port E of the 232D4SS8 (address zero) you would form a string like this:

SW0E$ = CHR$(2) + "0" + "E"

You could then send SW0E$ to select port E. Similar strings could be used for turning on the other ports. To turn off the ports the string might look like this:

TOFF$ = CHR$(2) + CHR$(2) + CHR$(4)

NOTE: There is no delay through the Smart Switch and the data is not buffered.

The four-character command adds additional security to port selection. The only difference between the four-character command and the three-character command is the addition of the ASCII ESCape character in front of the three-character command.

The first character is the ASCII ESC character (decimal 27). The second character is user-defined character. The third character is the desired port address (0). The fourth character is the ASCII upper case letter of the desired port. Refer to the "Three Character Command String" section for more information regarding the last three characters.

Example 1: To turn on port E of the 232D4SS8 (address zero) with ASCII STX set as the user defined character.

Send to Master port: ESC STX 0 E

(27 2 48 69 decimal)

14	Documentation Number 232D4SS84502 Manual

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