some questions about parallel port

[zaman]

hi
you can turn on and of LEDs througt parallel port by data port
please help me in my that question
i have LED that already glow not through the parallel port but some there sources means i want to interface my glowing LED i need p how i can ascertain wheather my LED is turned on or off through intefacing my glowing led with my parallel port please help me how can i do this
if some body will provide me programe in CPP or any other language
i m thankful that person

waiting for response
zaman

[HWman]

I expect that the LED is controlled through some other device and you want to get it's state to the PC through parallel port.

One idea to get the state of LED to computer is to take a suitable optical sensor and put it near the LED in such way that the light from LED shines to the sensor well, but no light from other soruces can get to your sensor. Then just wire the state of the sensor to the PC parallel port input pin. In simplest cases just wiring a phototransistor

There is some information on parallel port input also at
http://www.epanorama.net/circuits/parallel_output.html

Also check "http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm" at
http://ourworld.compuserve.com/homepage ... /page6.htm

From theat document you cn find the circuit


I think the idea would work just putting the phototransistor in place of one switch in the circuit.

[toni ross]

pls. do help me..i nedd info about parrarel port and how to manage and control it..programming a pararell port using a visual basic

ty very much

[HWman]

Check out those links:

Programming The Parallel Port In Visual Basic
http://www.aaroncake.net/electronics/vblpt.htm

Parallel Port Central
http://www.lvr.com/parport.htm


From the later:

Use Inpout32.dll from http://www.logix4u.net/
Here are definitions for input and output routines:

Attribute VB_Name = "InpOut32_Declarations"

'Inp and Out declarations for port I/O using inpout32.dll.

Public Declare Function Inp Lib "inpout32.dll" Alias "Inp32" _
(ByVal PortAddress As Integer) _
As Integer

Public Declare Sub Out Lib "inpout32.dll" Alias "Out32" _
(ByVal PortAddress As Integer, _
ByVal Value As Integer)