The file directory is digitally signed against that exact CID. When inserted, the navigation unit issues a low-level proprietary CMD42 execution block sequence to lock the card permanently to prevent duplication across vehicles.
: You must purchase a physical, pre-loaded SD card from an authorized Volkswagen Parts Department or the VW Navigation Store. These cards are "single-use"—once inserted, they lock to your vehicle's VIN and cannot be used in another car.
To help point you in the exact right direction for your update, could you tell me: What is your vehicle? download RNS 315 v.4 Map Update - SD Card
There are several reasons why you should consider updating your RNS 315 maps:
Because these specific rewriteable SD cards are incredibly difficult to find today, downloading a raw file online is generally impractical for the average user. How to Safely Acquire the v.4 Map Update The file directory is digitally signed against that
RNS 315 v.4 (and subsequent versions like V12) map update is primarily distributed via physical pre-loaded SD cards
Before downloading and installing the RNS 315 v.4 map update, consider the following: These cards are "single-use"—once inserted, they lock to
directly to the root of the SD card.
Before purchasing any update, confirm you actually have an RNS 315. It looks almost identical to the RNS 510, but they update differently (the RNS 510 uses DVDs, while the RNS 315 strictly uses SD cards). To verify your system: Press and hold the button for about several seconds. Select Versions on the touchscreen.
The RNS 315 should detect the new map data.