B&B Electronics Parallel Port Input/Output Converter PPIO Benutzerhandbuch

 

 

PPIO2899 Manual 

 

27

 

Each output of the PPIO is capable of handling currents as high 

a 500 mA when the output is low. This means that you can connect 
a relay or a light or other load between the output and a positive 
power supply voltage. See Figure 3  for an example output. 
Whenever the PPIO output in the example is LOW the relay will turn 
ON and close the contact. To turn ON the relay you should use the 
force I/O ON portion of Table 2. Of course, if you use a 24 volt relay, 
you will need a 24 volt power supply. The PPIO will control devices 
up to a maximum of 50 volts DC. 

 

 

 

Each input of the PPIO works with voltages up to 50 volts DC 

with a threshold of 2.5 volts. This means that to force a LOW the 
PPIO input must be below 2.5 volts. To force a HIGH the PPIO input 
must be above 2.5 volts. If you leave the PPIO input open it is the 
same as a HIGH input (above 2.5 volts). See Figure 4. In the 
example if the temperature is below 72 degrees the thermostat will 
be open and the PPIO input will be HIGH. The bit that is read into 
the computer will be a ZERO (negative true logic). When the 
temperature goes above 72 degrees the thermostat closes and 
forces the PPIO input to ground giving you a ONE in the computer.