12
SERIAL
↔
PARALLEL CONVERTER IV
4. Turn on the serial device (terminal or serial
printer).
The Converter will send the self-test message
continuously to the serial device until DIP-switch
Position 6 is turned off. Once the self-test is disabled,
you can connect to the parallel input device, and send
data normally.
Do not
make the parallel connection until
the self-test is complete.
Note that a PC’s parallel port usually has pull-up
resistors embedded at the port, and this condition will
typically provide enough power to enable the Converter.
If this is the case, dropping DTR and RTS at the
Converter’s serial output will not be enough to turn the
Converter off or to reset it, since the Converter will still
be drawing power from the PC’s parallel port and thus
will remain on even though the serial output port has
had power removed from it. To reset the Converter in
parallel to serial mode, you might have to turn the PC
off and back on again while the serial device is off (or
while its leads are low), so that voltages on the parallel
port drop.