how to program the I/Oport of PIC16F84 in Multisim 9?

[pub_longb]

hi, I am using the PIC16F84 as the MCU in my circuit, and the function of it is using  the bi-direction ports to read the ADC output digital signal and further to transfer the signal to the VDAC. But I met the problem that the port make the input of the VDAC all become zero. Why ?
I attached the circuit, hope to get the answer.
Thanks a lot!

[lacy]

I don't know if this has anything to do with your problem, but I did discover an error (I think). On your Pic you have a Bus3 going to RA0 and on the "Sleep" Switch you have it labeled as Bus2. I believe these have to be named the same in order to make the connection, otherwise the are going to two different busses. Try renaming them and see if this works for you.

If it has something to do with the PIC, then Nestor would probably know more about that than I. I thought I would just point out this connection error just in case that was the problem.

[pub_longb]

Thanks Lacy,
This is defenitly one problem in the circuit, but it can still not solve the main problem. the inpurt of the VDAC still be all zeros.
I think maybe the I/O port of the PIC16F84 has some limitation ? I have no idea of it.
Hope for some help! Thanks!

[JohnBVZ]

Send me across the schematic picture.  I can have a look.

- J