The VPM upgrade is supported only by the current firmware version of your computer and only when set in technical open-circuit or rebreather modes (i.e. recreational open-circuit mode is always Bühlmann.) An unlock code to enable the feature in the firmware is returned to you via E-mail within 72 hours.
Perdix is a continuation of the well-known and respected in the market dive computer Petrel. Smaller, more trips and more compact Perdix has a mode OC, CCR in both recreational and technical.