Along a few years we have developed an Open Source driver (C language, Linux OS),for the PCI-6221 board, based on NI DDK. This driver worked well and we moved to faster boards in the M family. While this was fine for a PCI-6251 board, we had a strange behaviour with a PCI-6259 board, with spikes in correspondence of specific input values (see attached pictures). Booting, in the same acquisition setup, a different OS (WINXP+NI-DAQmx or Scientific Linux 6.3+NI-DAQmxBase 3.5.0) gave correct signals, with no spikes.
Is there some peculiarity of the pci-6259 board inside the the M family?
Giovanni