Where I used to work, we used JTAG in the production environment to test the basic connectivity and operation of ocb's prior to the full functional test. We used a in-house test executive derived from the NI CVI toolkit, and a series of generic instrument modules underneath this to provide the instrument support. One of these instrument drivers was to talk to the JTAG S/W... The basic JTAG s/w used was from a company called JTAG Technology based in Holland. Originally they provided a DDE inteface to their s/w, so basically the JTAG instrument driver acted as a DDE client, and packaged messages from the test executive through to the JTAG s/w. Later on they released a DLL version of the JTAG s/w with (so say) a CVI interface... I'm not sure how that went, as I left t
he company shortly after, but it may be a way forward for you...
Cheers
JB