Parallel port VIs apparently not opening the port

[K C]

Hi,
At this moment I am using the parallel port for interfacing to a board to set parameters inside a IC.
I am using the write port function to write directly to the parallel port registers.
Is this an option ?

[TheWay]

Hi KC,
 
Yes, parallel port communication has been supported since VISA 1.1. Refer to think link for a simple example:
<a href="http://zone.ni.com/devzone/cda/epd/p/id/4213" target="_blank">http://zone.ni.com/devzone/cda/epd/p/id/4213</a>
&nbsp;
Regards,
Way S.

[K C]

Hi,
&nbsp;
I was not referring to VISA.
If you want to use the parallel port in a normal way (printer port) I would suggest that you use VISA.
&nbsp;
But if you need a parallel I/O port on your PC then it is easier (and faster) to use direct port access.
With the direct port access you have full control over all the data and, more important, the control bits.

[K C]

Hi,
&nbsp;
I don't know which examples you use, so I can't comment on that.
&nbsp;
See attached VI It writes data to port 0x378 (standard parallel port) Data is inverted every cycle.
This should toggle all the data bits.
&nbsp;
I don't if a software tool like portmon will see this. You have to check the data bits on the connector.
&nbsp;
What can go wrong:
&nbsp;
Your PC port address for the parallel port is different. Not likely, but you must be sure.
&nbsp;
You are using an old version (before 7) of LabVIEW and/or an old version of the Write port function in combination with XP or NT (assuming you are using Windows)
&nbsp;
Let me know what this VI does on your machine.


write par port.vi:
http://forums.ni.com/attachments/ni/70/7536/1/write par port.vi

[K C]

Hi Adam,
&nbsp;
Because of the levels and the long interface lines you should use a buffer IC to get the signals at the right level and to protect the circuits that you want to connect with the parallel port.
You can use a 74LS241 or something like that. It also depends on the levels you need.

[K C]

Hi Adam,
Nice to see it's working.&nbsp; :smileyvery-happy: