My Purchase experience MB STAR Diagnosis System Compact3

I purchased a Chinese MB STAR Diagnosis System (SDS) Compact3 (C3) on the Internet purely  for educational purposes and so that I could experiment with some of the settings in my W220  S500, especially to do with my pet subject, the Automatic Climate Control (ACC).


Purchasing, owning, setting up and using a SDS has turned out to be an extremely difficult project and one not to be undertaken lightly. There is a plethora of information available on SDS on the Internet but unfortunately it is mostly non constructive, quite often abusive, and fairly often not available without paying a fee to some very enterprising people. My SDS as supplied came without any installation instructions other than a couple of crude videos and an out of date pamphlet for the RS232 Card.

After a lot of assumptions and several emails to the supplier, I eventually got connected and began cautiously testing the various functions and capabilities of SDS. I particularly like the Workshop Information System and the StarFinder applications and have used them many times to date. I have yet to have a real need to use DAS but began self training just in case, and progressed to the point where I could exercise the cabin lights (easy to watch from outside the vehicle) and got to the stage of opening and closing various flaps on the ACC. I was able to read out the list of fault codes stored in my vehicle and was surprised to find a transmission issue which has been there for several years.

I then learnt the hard way that installing and switching on the SDS on a laptop connected to the Internet results in the system automatically downloading SDS “Addons” and in the process, it seems, being “Black Listed” by MB thus preventing the MUX from working/connecting. I could still use Xentry in simulation mode, ie with no vehicle connected, and this is extremely useful for training purposes, but I just could not get the SDS to connect again to my vehicle. It took me two months of full time research and experimentation in order to recover from my predicament. I then ran into the problem that it seems all Benz Star diagnosis C3 SDS have in that they are prone to cease working three months after the date of the SDS Version. In my case an application or “patch” was provided which reset the SDS software. My guidelines should avoid the need to do this in future as I now always configure the laptop date at my SDS Version plus one month, at the start of each session.

My most important and unexpected discovery was that the RS232 data link is temperamental if operated at the recommended baud rate of 115,200 bps. It seems that the MUX provided could not cope with these high data rates. My SDS worked at 57,600 bps but to be on the safe side I have set host and guest COM2 settings to 19,200 9,600 bps and the SDS is now very reliable and connects every time. (Later note: I now have set COM2 baud rate to 9,600 bps as it seems even more stable. I couldn’t be bothered changing all the figures. I just replaced ‘19,200’ with ‘19,200 9,600’ throughout the document.) I also think the order in which you connect is important and I have slightly adapted a procedure suggested by Taztheman.

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