. I am using a PCI-1200 with 3 8255's. I wish to configure port a to all digital outputs. I want to control the states of the individual lines with boolean switches. I seem to get a strange mix of states on the outputs when I have more than one switch.Have you looked at the examples? There's one called Write to 2 Dig Ports(8255).vi. It uses front panel Booleans and it looks easy to modify for three ports.