This post contains five parts: SCN system definition and importance; SCN coding importance; SCN coding compatible hardware SCN connect c4; how to use SCN connect c4 to do SCN coding; case study on SCN connect c4 perform do SCN coding.
- SCN system definition
I fully agree with the point about the potential for misconfiguration and unreliability, but as someone who has worked in driverless vehicles and aviation all my working life, I think that it’s slightly emotive to justify some of M-B’s behavior on the grounds of safety.
Yes, certain functionality in some ECUs is definitely and inescapably safety critical and will be designed and written to the equivalent of DO-178B Level B/C (think of the consequences of cruise control going rogue, or separation radar getting its decimal point in the wrong place).
Those elements of code and equipment will be partitioned away such that the remainder of the vehicle can be changed/update/reconfigured as required without requiring the entire vehicle to be re-qualified.
A simple analogy being that Airbus don’t want a change to the In Flight Entertainment system to require them to re-qualify the Flight Control System software. What they do want to do however is ensure that Blue Ray player type X will work with Controller Y and Screens Z – and that if the controller needs to also work with a particular comms system then it can be coded accordingly.
For that reason a lot of time and effort is put into partitioning functionality such that the (re)qualification impact of in-service design changes can be minimised. That is in all cases except Eurofighter Typhoon where partitioning was done to meet political workshare agreements.
Whilst I’m sure that the entire SCN system is managed to suitably high pseudo-safety-critical standards within the Design Organisation (i.e. Mercedes Benz), I’d be seriously amazed and impressed in equal measure if their dealers have the same level of quality in any ICT device that is connected to the vehicle.
I just don’t believe that the dealers’ ICT is under sufficiently tight configuration control for that to be the case. Moreover I bet that each dealer’s insurer doesn’t realise that they are taking responsibility for safety critical software otherwise their indemnity premiums would rocket.
Instead I suspect that in fact SCN is intended to maintain a degree of configuration control which has, until now been absent in the vehicle industry, and as you rightly say is necessary to ensure compatibility across multiple sub systems.
With the advent of greater levels of vehicle autonomy I suspect that the ‘quality’ standards will have to evolve even more – probably to the point of locking the dealers out of certain systems, but I doubt that they’re there yet.
SCN was definitely used initially on SRS (we can understand why mis configuration there is a safety issue) Engine/Gearbox – to ensure people didn’t configure wrongly and cause emissions problems (I think this was because of the USA emissions regulations)
– It has then been extended across the whole vehicle (starting with the instrument cluster on the W164 when it was launched).
The “configuration control” that was enforced between SCN coding was to only allow certain things to be altered using Star Diagnosis (with a password protected engineering mode that allows the very knowledgable support people in Germany to instruct a technician in a workshop how to change other parameters). This still allowed technicians to code things wrongly (and have to have more training!)
I see less and less control / modification being allowed within the retail/repair “network”.
- SCN coding importance
The move to SCN coding was *very* important. There are too many configuration items in every ECU now to have someone set options by hand whenever an ECU is changed, or to understand how changes on one device have to be done on other devices. These cars are really very very complex, and unlike your laptop, if something goes wrong can result in fatalities.
There are software dependancies between different ECUs, and actually loading software into ECUs is now needed regularly – and thus so is up-to-date diagnosis equipment and up-to-date firmware disks too. A simple example is the Audio system. If you update the firmware in the COMAND unit the firmware in every other MOST device needs also to be compatible (if you want it to work reliably) and thus they all need firmware updates. If you change one component then all components need to be updated to be properly compatible.
The latest equipment even now uses ethernet to load firmware into some ECUs (so it takes 20 minutes not 20 hours).
Without SCN coding it would take considerably longer to change any control unit, would result in mistaken configurations, and thus the cost of repair (or re-repair) would go up and up as systems got more complicated. SCN coding basically allows the correct configuration to be loaded into the car.
Imagine what could/would happen if you had to “hand code” the airbag controller after replacing it ? Would you trust all of your airbags to work after the local mechanic had to set all the options correctly ? I certainly would not.
Your comment that “The capital cost of the latest version, plus the monthly subscription, means it is beyond the reach of many smaller independent garages” is just wrong.
If your garage has the skills to deal with the technology (and i’d argue that if they don’t they shouldn’t be doing complex things with the newest vehicles), then it is completely affordable.
If you want to work on older cars, then most independents seem to use a clone machine and use it for limited things.
The EU competition commissioner has previously taken a good look at this market and enforced rules that mean diagnosis equipment (for newer vehicles) is available at sensible prices. This is not true in the rest of the world. Mercedes diagnosis systems in USA are more expensive, and in the far east (and I think Australia) are not available at all to independents.
Sorry to be so contradictory, and in summary, but without SCN coding there would be mis-configurations and un-reliabilty – possibly dangerous to life – occurring quite regularly. And if you are going to need to work on newer cars, there are very affordable Xentry diagnostics systems – you just need to talk to Mercedes.
- The Mercedes Benz online SCN coding hardware:
MB SD C4 only
- The three version of Xentry DAS is able to do SCN coding: Xentry DAS 07, v2015.09, v2015.12
- How to use Mercedes Benz v2015.07, v2015.09, v2015.12 to do online SCN coding:
- For the users who own mb sd c4 v2015.07 or v2015.09 or v2015.12, you just order SCN Online Coding service (Item No. SS99).
- If you MB SD C4 software is before than V2015.07, you are advised to buy the newest sd connect C4 update software, then order SCN Online Coding service (Item No. SS99).
- Before order SCN Online Coding service (Item No. SS99), please you provide our customer service your car model, year and SCN coding function & system (for example EZS, command navigation, ect), then our customer service with confirm with our factory engineer whether they can access to the authorization, then notify you make payment. Feature: convenient and fast, online authorization.
- ) Place an order on our website for this online coding service.
- ) Contact our online customer service on skype:obdtool.co.uk or our Live Chat system
3.) Prepare mb sd c4, car, laptop and teamviewer.
4.) Send Teamviewer ID and Password to customer service
- ) Factory engineer will access to your laptop to open this function directly, you do not need do anything
- ) After it done, system will prompt you “The SCN coding sequence has been completed successfully”, we will inform you as well
- I have MB Sprinter 2006 WDB9066331S102752, and I own MB SD C4 V2015.09, I want to access to EZS scn online coding function.
- I have MB Vito 115 CDI-2006, and I own mb sd c4 v2015.09, I want to access to EZL module.