The Pockels Cell and mirror output boards are typically not the same. In this case, it is required that the clocks of these boards be synchronized to ensure that flyback blanking, and other Pockels functionality, remains phase locked with the fast mirror line scan signal.
In ScanImage 3.0, this clock synchronization was done by using the RTSI7 terminal (also termed RTSIOSC) on the RTSI (Real Time Synchronization Interface) connectors available on the National Instruments boards.
In ScanImage 3.5, synchronization occurs via the terminal specified in the Rig Configuration section of the INI file. It can be any terminal from RTSI<0-6> or PFI<1-15>. The user must connect the specified terminal on each of the boards to each other. Additionally, the digital ground (DGND) terminal for each board should also be wired together.
Note that RTSI7 (RTSIOSC) is NOT an option for the clock synchronization terminal in ScanImage 3.5.
The default INI file setting in ScanImage 3.5 is to use RTSI6. Using this default, ScanImage DAQ boards are connected (synchronized) as displayed here:
Typical (default) Clock Synchronization Scheme via RTSI 6 Terminal
As can be seen, the RTSI6 terminal is the second terminal from the end of the board (PIN 32). Its associated ground pin (PIN 31) is also connected between the boards.
Some users may prefer to use a Programmable Function Interface (PFI) terminal instead. This would allow the synchronization to be connected via breakout box (e.g. National Instruments BNC-2090) terminals, without using the RTSI connectors inside the computer box. Using the RTSI connector, however, ensures short cable lengths and, therefore, high clock signal fidelity.
New Variables
outputBoardClockTerminal: Specify terminal, either PFI<1-15> or RTSI<0-6>, which will be used to synchronize the clocks of the acquisition/mirror board to the Pockels cell board (if present). Previously RTSI7 was assumed/required.