Previously I was using CBR_9600 when communicating with 9600 baud devices. But there does not seem to be a CBR_28800 setting. Is it possible to set the baud rate using the DCB structure of 28800?
According to MSDN, the baud rate can either be one of the defined constants (such as CBR_9600, CBR_38400, etc) or any integer value. The constants are just defined to the values, so it's not really an enumeration at all. From the link:
The baud rate at which the communications device operates. This member can be an actual baud rate value, or one of the following indexes.