set unit_found [ adf_avl_check_unique_id_wrap $hw_type $unit_id ]

if { $unit_found } {
    # if HWDetector - magic done here:
    set unit [adf_avl_get_unit_by_unique_id_wrap_safe $hw_type $unit_id $conn ]
    # ... work with unit on Regular HW
} else {
    # Unit doesn't exist at all, maybe try to check other HW Type
}