At 250 MHz samples are taken every 4 ns. The module has eight input channels grouped in four 2-channel groups. The resolution of the samples is 12 bits over a range of 10 V. This corresponds to 2.5 mV signal resolution.
The firmware of the module in use (version SIS3320-250-M-2A02-1-v103) allows for a dedicated accumulator mode. For more information about the SIS3320-250 (including addressing and settings), refer to the User Manual.
The SIS3320 has a large number of options, and they are all very similar. You can do many things that are all almost the same, but different in some important details. Here are the definitions that are relevant to the Compton photon detector read-out.
- Triggering: A trigger can be used to start the sampling or to stop the sampling. The trigger can be generated from the external front panel lemo connector, or through an internal VME key address write. A pre-/post-trigger value can be defined to delay the external start/stop or autostart/internal stop.
- Memory page: Pages of 32MSamples / 4^n can be defined (up to 64 samples small). When pages are used, they are automatically in circular buffering. To do the same with single shot buffering, one has to use the "sample length stop" to limit the number of stored samples after a trigger is received. Upon reading the ADC memory over VME, pages up to 8Mb can be used.
- Single shot buffering strategy: the trigger defines the start of writing samples to the buffer until the buffer (or page) is full or a predefined memory depth has been reached.
- Circular buffering strategy: Every sample is written to the circular buffer (or page) and the trigger defines the stop. The stop pointer is also the start of the event and stored in the event directory. A bit in the event directory indicates whether a full wrap-around was completed before the stop.
- Single Event mode: The full memory of 32MSamples is used as a big circular buffer or as single shot memory.
- Multi Event mode (ENABLE_MULTIEVENT): The memory is divided in pages or events for the acquisition of shorter signals. Up to 512 stop pointers for the individual pages are stored in the event directory. "Sampling logic armed" is cleared after last event.
- Autostart mode (ENABLE_AUTOSTART): The ADC automatically advances to the next page in multi-event mode and starts sampling in the circular buffer. Sampling starts with the "Sampling logic arm" command, and in multi-event mode with the end of the event on the previous page.
- Accumulators: Each of the 6 accumulators have a 24-bit counter and 36-bit sum (for definitions of when which accumulator is filled, see user manual). They are stored in the event directory and cleared at the beginning of every event. When accumulators are stored, only one event can be stored in the event directory in multi-event mode :-(
Modes of operation
These setup modes are accessible in the CRL through
where mode is the mode number.
Common flags: ENABLE_LEMO_START_STOP DISABLE_INTERNAL_TRIGGER ENABLE_MULTIEVENT
DISABLE_AUTOSTART ENABLE_WRAP_PAGE_MODE ENABLE_ACCUMULATOR PAGE_SIZE_16M_WRAP
|Long buffers, lemo start and stop|
DISABLE_AUTOSTART ENABLE_WRAP_PAGE_MODE ENABLE_ACCUMULATOR PAGE_SIZE_512_WRAP
|Short wrapped buffers, autostart, lemo stop|
DISABLE_AUTOSTART ENABLE_ACCUMULATOR ENABLE_SAMPLE_LENGTH_STOP PAGE_SIZE_16M_WRAP
|Multievent, lemo start, stop at preset number of samples|
ENABLE_AUTOSTART ENABLE_WRAP_PAGE_MODE PAGE_SIZE_512_WRAP
|Multievent, lemo start, autostart, wrap around, no accumulator|
Last update: wdconinc 18:29, 14 October 2009 (UTC)
|LED assignment||LEMO control in/out|