I have a milling machine equiped with a 3 axis dro from Sino type SDS6-3V. It measures the table in X and Y direction, and the head in the Z direction. It works well, only the pinole is not measured and that is what I want to add to the dro.

Recently I found that Sino also has 4 axis dro's, and I was looking into the SDS6-3V4 and the SDS5-4V. Scanning the internet I only find short summaries what the dro can do, but detailed information is hidden very wel. After asking around I ended up at the european representative answering a only few simpel questions, but also telling that they don't supply detailed information because they are afraid for the competition. Also looking at a picture of the SDS5-4V an lcd graphics screen can be seen with pixels clearly visible and the summary tells there is a powerfull 32 bits microcontroller inside. Another feature of the SDS5-4V is that is can be connected to a computer, but there is no information what that is good for. What is the benefit having that computer connection? Asking the representative for further information he even denies there is a graphics display and is refusing any more detailed written information (a manual or so could help).

So I am looking for good information about the dro's mentioned that I can figure out which one would be the best choise for me. Also, since there are more dro's available, suggestions for other brand of dro's are welcome too.