Specifications

Chapter 5

Timing Modes

The Princeton Instruments ST-133 or ST-133A Controller has been designed to allow the

greatest possible flexibility when synchronizing data collection with an experiment.

The chart below lists the timing mode combinations. Use this chart in combination with

the detailed descriptions in this chapter to determine the optimal timing configuration.

Mode Shutter

Free Run Normal

External Sync Normal

External Sync PreOpen

Continuous Cleans Normal

Continuous Cleans PreOpen

Table 3. Camera timing modes

Full Speed or Safe Mode

The WinView/32 Experiment Setup Timing tab page allows the user to choose Full

Speed (Synchronous) or Safe Mode (Asynchronous). Figure 10 is a flow chart

comparing the two modes. In Full Speed (Synchronous) operation, the ST-133 or

ST-133A runs according to the timing of the experiment, with no interruptions from the

computer. In Safe Mode operation, the computer processes each frame as it is received.

The ST-133 or ST-133A cannot collect the next frame until the previous frame has been

completely processed.

Full Speed operation is primarily for collecting “real-time” sequences of experimental

data, where timing is critical and events cannot be missed. Once the ST-133 or ST-133A

is sent the Start Acquisition command (STARTACQ) by the computer, all frames are

collected without further intervention from the computer. The advantage of this timing

mode is that timing is controlled completely through hardware. A drawback to this mode

is that the computer will only display frames when it is not performing other tasks. Image

display has a lower priority, so the image on the screen may lag several images behind.

A video monitor connected to the VIDEO output will always display the current image.

A second drawback is that a data overrun may occur if the number of images collected

exceeds the amount of allocated RAM or if the computer cannot keep up with the data

rate.

Safe Mode operation is primarily useful for experiment setup, including alignment and

focusing, when it is necessary to have the most current image displayed on the screen. It

is also useful when data collection must be coordinated with external devices such as