Piezo fast axis

If a piezo is the fast axis (such as in piezo, focus, or contrast scans), we will use the internal timer of the NI-PCI-6534 board as conductor of the orchestra. The configuration is done by a call of DIG_Block_PG_Config() with the following parameters:

Config = 1 (pattern generation with REQ edge latching)

ReqSource = 0 (REQ source from onboard counter)

ExtGate = 0 (not used on this device)

TimeBase = -3...5
This parameter is chosen depending on the dwell time, such that the time base is as short as possible (-3=50ns...5=10ms)

ReqInt = DwellTime_ms/TimeBase_ms.
This parameter sets the time interval between REQs to be the dwell time, where $DwellTime\_ms=Timebase\_ms \cdot ReqInt$. As a result, ReqInt is the number of time bases passing within the dwell time.

At each new pixel there will be a high pulse out of REQ, whose edge will be rising simultanously with the data flip and go back to low one time base later. The time base is always chosen to be as short as possible. So except for unrealistically short dwells it is negligibly short compared to the dwell time (less than 1/3000). This falling edge will signal that the data is stable. Jumper E6 of the DeltaTau boards will be in the OFF position indicating that low ICLK means encoder latched. As a result, the output from REQ (pin 2) on the NI-PCI-6534 will be an input to ICLK (pin 46) on the DeltaTau (and other devices) and the falling edge will signal the begin of the next scanpixel. Note that ReqInt can be chosen to be a number between 2 and 65535, so that dwell times between 20 $\mu$sec and 655.35 msec can be chosen in 10 $\mu$sec steps.