> 
> The original idea behind the hv driver is that all voltages in the ODB and the class driver are
> positive. If you have a negative power supply, then the voltage is inverted at the device
> driver level. That's why you have MIN and MAX in the class driver.
> 

This rings a bell. I used the hv class driver to write a frontend for the L1440 mainframe (negative voltage),
on ODB it will be positive values, when writing to the device I had to add a minus sign,
and when reading back they came back negative and I had to add an fabs() in the comparison
between readback and demand.

Persons with bipolar power supplies need not apply.

K.O.