When specifying the channel string either in the DO ActiveX control or through the .ChannelString property, just select both ports. For example, to group ports 0 and 1 together, type in 0,1.
I'm using the DIO object. I just want to send a 16 bit word value to a port, not generate a waveform. I've have tried to use the channelstring property. I also tried using the Named Channels using the Data Neighborhood in NI-Max, but neither lets me group 2 ports together. I checked the user manual but I couldn't find any info stating I could or couldn't group 2 ports on the DIO-96