Piezo fast axis scans

For $(x,y)$ piezo scans, we will calculate the sequence of XPZT and YPZT positions for a scan line, or perhaps for the entire scan. These digital positions will then be streamed from the NI PCI-6534 to the Delta Tau system, and a constant desired position will be set for ZSTG. The REQ1 output of the NI PCI-6534 will be the source of the master clock (the board will be operated in pattern generation mode by a call to DIG_Block_PG_Config() as described in Sec. 7.1). The Delta Tau PMAC2 system will then drive the piezos and the ZSTG motor accordingly. If a $(x,z)$ or $(y,z)$ piezo scan is desired, then XPZT and ZSTG, or YPZT and ZSTG, outputs will be streamed to the Delta Tau system.