Use a pic with a hardware uart, write the program to monitor the push
buttons and write an ISR to monitor the RS485 network.
Regards
Stuart

Mathew Cohen wrote:
>
> I am constructing a device that sits on a rs485 network. The device
> constantly listens to the network for information that may relate to its
> device number. The device also has 16 push buttons that need to be monitored
> at the same time. I am currently using a shift register to clock the push
> buttons in.
> The concern is I am using PicBasic Pro and it's serial routine either waits
> for a character berfore continuing on with the rest of the program,which
> does not help tracking the button status.  Or has a time out which the
> lowest timeout  is 1ms. This leaves a lot of time for other thing to be
> missed.
>
> Can someone suggest how this could be done effectively.
>
> Mathew Cohen.