Update pmbus to use Pandas more efficiently
Update pmbus to use Pandas more efficiently

cathalmccabe/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,Xilinx/PYNQ,yunqu/PYNQ,cathalmccabe/PYNQ,Xilinx/PYNQ,yunqu/PYNQ,schelleg/PYNQ,Xilinx/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,Xilinx/PYNQ,yunqu/PYNQ,yunqu/PYNQ,Xilinx/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,yunqu/PYNQ