I'm not sure why you can't change the port usage. In Panelbuilder32, it looks like you only have 1 port with the DH-485 option selected. See the attached screenshot; a comparison between a DH-485 and DH+ PV600 touch only. The DH+ has a 232 port and you select the usage for this port.
I needed to click the "part numbers" button to select the PV I was actually looking for. The DH-485 second 232 port does seem to be strictly a printer port. The DH+ second 232 port shows as DF1.