keithmech
I think the long and the short of this was that the various opto-isolation bits and pieces on the breakout board were destroying the signal from the speed sensor.
As I said fairly early on in this post, the signal from your speed sensor - providing it is NOT above 5 volts - and if you have a scope, you can check this - should be fed DIRECTLY back to your computer via one of the input pins. Mine is and works perfectly - but then I don't have this fancy Campbell break out board, all my signals go directly back to the computer.
Jim