USe this search it should give you places to get your info

https://www.google.com/search?q=Mach3+Modbus+Commands&ie=utf-8&oe=utf-8

Yes i have searched on google and read al kinds of manuals... But i cant access modbus directly from VB scripts. I cant find any working examples on the net that work with arduino modbus.
Anyway i made it work using UserLEDs (1000 and up) so there is no need for me to directly access modbus from vb scripts i use brains as a pass troug so thank you very much for your idea for using DROs ) and thank you for your time