ok so no replies asof yet so let me ask a different question... after each serout command sent to the datalogger they call the fuction
GOSUB GET_SERIAL_BYTES ' Purge Received Buffer


GET_SERIAL_BYTES: ' Subroutine to get serial byte data

serin2 rx,84,100,phase_out,[iobyte] ' Get byte data
buffer[index] = iobyte ' Load buffer with IOBYTE
index = index + 1 ' Increase the buffer size
if index > 30 then PHASE_OUT ' if more than 30 phase out
return

PHASE_OUT: ' timeout buffers too big
RETURN

I am not familiar with UART communications. Could this purging function be ommited when using SPI?