Hello roco_2nd,
Your PCI-6143 device is supported under the NI-DAQmx driver. You can program with the NI-DAQmx driver in Visual C++ 6.0. A great resource for determining what text-based programming options are available with National Instruments data acqusition drivers is the following Knowledgebase:
KB 317742FQ: Programming NI-DAQ in Text-Based LanguagesThe links in the table go to additional resources telling you how to go about programming in different environments and where you can find pertinent examples.
I hope this helps,
Travis G.
Applications Engineering
National Instruments
www.ni.com/support