Re : Can simulation interact with serial or parallel port pins?

[racbon]

Hi all,
I am using Multisim 10. I plan to make some circuits that could be controlled with the PC's serial or parallel port pins. I'll design applications that control the circuit by sending signals to one of these ports. My question is:
Is it possible in Multisim to connect the schematic to a pin of the serial or parallel port and make it interact with it during simulation?
Any help or advise will be appreciated.
Thanks.

[lacy]

The only way I know of interfacing Multisim to do what you want is through Labview. I am not that versed on Labview, but I believe it can acquire signals and store them in a file and then that file can be used in Multisim as input signals to a circuit

This may be reverse of what your looking for and I am not sure if you can go the other direction with Multisim or not. I will let The NI team take this further as NI has numerous devices and products that may be able to accomplish your goals here.

I hope I was maybe of some help.

[racbon]

Thanks lacy for your reply.
Before posting my question, i've read a lot of articles and tutorials about LabView. But it seems that it does not correspond to what i want to do. I need some real time interaction between the circuit and the port's pin. One friend told me to try to create an instrument in LabView or LabWindows and use it in Multisim. This instrument will continiously read the state of the port's pin and inject it in the circuit during simulation. But according to LabView documentation output instruments could be used only before simulation. I hope i m wrong...
Why is it so hard to implement such a basic feature in Multisim?

[GarretF]

Hi Racbon:

You are correct that Multisim cannot simulate with real-time data, but as you noted, you can collect read data and feed this into Multisim.

For the question why is is hard to implement, there are a couple of reasons inherent in SPICE simulation. The most important is that simulation does not occur in real time, it is much slower. But even if you has sufficient computing power to simulate in real time, SPICE simulation sometimes goes backwards in time. Going backward in time is a fundamental "property" of SPICE simulation. So while you are acquring real time data, simulation may be going in the opposite direction! In theory, you could also solve this with sufficient computing power (by always taking very small time steps). All combined, todays best personal computers would need to increase their computing power several or more orders of magnitude.

[racbon]

Thanks koekje for the explanation. I now understand why it is impossible to make Multisim interact with port's pins in real time.
I'll try to create a verilog component that will behave as expected by imitating a serial or parallel port. I hope this will work.
Thanks a lot guys.