OnlineTool After replacing a BMW control unit, coding may be required to set it up for the vehicle's equipment. Those settings are contained in NCD. Some units only accept digitally signed coding data, so they need a signed NCD.
This guide explains the file's contents, the purpose of the signature and how prepared data are written to a vehicle.
What NCD contains
NCD means Net Coding Data. It contains the values of a unit's settings, determining how that unit works with the equipment in a particular vehicle.
A unit has both software and settings. Coding writes settings; programming changes the software itself. Applying NCD does not mean that the unit has received new firmware.
The E-Sys unit list includes CAFD entries. CAFD describes the coding parameters, while NCD contains their values. A CAFD identifier and version distinguish one coding description from another.
After a software update, the unit's name may stay the same while its CAFD version changes. Check an older NCD against the new version. A unit may also have several CAFD entries that each require their own data.
What a digital signature does
A signature lets the program check who signed the data and whether they changed afterwards. It can detect changes to settings in a prepared file. The check is performed by software; the word “signed” in a file name is not a substitute.
With Secure Coding, the unit requires signed data. ISTA prepares and writes these data as part of its protected coding procedure.
The file must also fit the vehicle and unit. Authentic data may still have been prepared for different equipment or software. Check both the signature and the file's purpose before writing it.
Keep the received NCD unchanged. Edited data need a new signature. When working with signed data in E-Sys, saving after editing starts the signing procedure. Viewing a prepared file does not require changing or saving it.
When signed NCD is needed
Signed NCD is needed when the unit requires it for coding. This depends on the unit and its software. The vehicle model and production year alone are insufficient to choose a file.
NCD provides settings. A function may also need installed equipment or a permission such as FSC. Coding does not remove those requirements.
Obtaining data through the NCD service
Preparation requires FA, describing the required configuration, and SVT, describing the units and software. The previous guide explains choosing this pair. Both files must relate to the vehicle and the state being coded.
The service uses FA and SVT to prepare the available signed NCD. It determines version 2.0 or 3.0 from these input data.
Keep the received NCD together with FA and SVT in the job folder. A note of the vehicle, date and purpose will help distinguish this set from others.
To apply the settings, the received files must be written to the corresponding unit through a diagnostic connection.
Identifying the unit for a file
In E-Sys, find the required unit and its CAFD entries. Compare their identifiers and versions with the information for the received NCD. A file name helps locate the result, but suitability must be checked against the program's data and the result description.
For example, an NCD prepared before a unit replacement may not fit the replacement unit's software. Check it against the replacement's CAFD first.
You can view an existing NCD in the E-Sys FDL editor. Its header includes the CAF identifier and vehicle profile. Leave the file unchanged when viewing it: editing and saving may require signing again.
Understanding a partial result
Sometimes the service returns data for only some requested units or CAFD entries. This is a partial result.
If two units need coding but data arrive only for the first, the second cannot be coded from that set. The first unit's file is not a replacement for the missing data.
Compare the required CAFD entries with the NCD received. File counts alone are insufficient because one unit can have several entries. Obtain missing data before writing to the corresponding unit.
Writing NCD in E-Sys
E-Sys 25.10.01 has a Coding module for coding individual units. First establish the vehicle connection, read or load FA and activate it. Activation calculates the vehicle profile.
Read SVT and find the required unit and CAFD. Read (ECU) reads information from the units. Read (VCM) reads it from VCM, which stores vehicle information. The previous guide explains the difference between these sources.
Read Coding Data reads the selected unit's current settings. After a successful read, expand CAFD to see the NCD beneath it. A copy is also saved in the CAF folder.
Distinguish the file read from the vehicle from the file prepared by the service. Read Coding Data retrieves the first. The second must be selected separately for the corresponding CAFD before writing.
Code NCD writes the selected NCD. Check which file is selected beneath CAFD before starting. Starting ordinary coding does not by itself establish that the received service file is being used.
E-Sys displays progress and produces a report. Check the result for the required unit, then check the vehicle function and diagnostic messages. This establishes whether the settings were written and produced the intended result.
ISTA organises Secure Coding differently. The action names above refer to E-Sys.
If the unit rejects the data
Start with the E-Sys message. A signature failure and a data mismatch require different checks. Keep the exact error and unit report with the job's input files.
For a signature error, check that you selected the original signed NCD without edits. For a mismatch, compare the file again with CAFD and the unit's software. If the cause remains unclear, the message, selected CAFD and file preparation details are needed to investigate.
Completion means writing to the intended unit without an error in the report and confirming that the required function works in the vehicle.
Obtain signed NCD
Prepare FA for the required configuration and SVT for the relevant unit state. Keep the inputs and check which CAFD entries have received data.
Orders are handled through the Telegram bot. Open the bot from the service page, check the selected service and follow its input instructions. Keep the result for the original procedure.