Thanks John,
to obtain a minimum result I had to put on 492 P: LISTEN at 0, TALK at 1 and EOI at 0. In this way on the HP 7470A emulator on the PC I select acquire from tektronix at address 3 and press "REMOTE" on the 492 P ,
"BUS ADD T0" and "NO LISTENER" appear on the 492 P screen. On the Prologix only the "TALK" led is on. The following message appears on the screen of the HP7470A emulator program: "Attemp to read from unsupported instrument model 'FINE OFF; DELFR OFF; FRQ RNG 1; MINATT +40; ........ CLIP OFF; WMFPRE WFID; FULL, ENCDG: ASC; POINT 500,250; RQS OFF; EOS OFF; CURVE CRVID: FULL, 72, 73, ...... ".
In the first part of the message it seems to me there is the configuration of the controls on the front panel of the 492 P and after the item CURVE CRVID there are a very long series of two-digit numbers separated by commas which I think are the coordinates in ASCII of the waveform to plot.

I don't know what to do, only the waveform data to plot should be separated and kept, but how ?

Thanks for your help

--Cheers
Attilio