In pxar corelib dacMax is included in the range. This means, shipping 256 as
value to uint8_t results in overwrapping to 0. This resulted in the DacScans
returning a scan from 0 to 0 -> empty data.
Reducing the "range" in pixel_module.py by one solves this.
use the exctrated dac range instead of requesting anew every time.