In article ,
RGR-74 wrote:

I tried to contact the Spex, but I have not any response,
I am not surprised ...

Unfortunately the documentation of this interface has been lost;
At this point I will make other checks and later I expand to other
control devices.

The input (at least in the configurations I have seen) takes pulses
from a photomultiplier operating in photon counting mode. The discriminator
then removes virtually all "dark" counts, and the output should (I think) be
pulses of uniform height that are fed to a counter.
Good luck,
Hans

--
Dr. Hans-Christian Becker
'96 VN750 SM5TLH KG6POK
Uppsala, Sweden