[Cs-framework-info] NI FPGA card as MCS

[Beck, D. <D....@gs...>]

Dear Colleagues,

I have implemented a simple solution for using a FPGA card from NI as multi-channel-scaler (MCS). By this, one can do time resolved counting of ion or photon signals. One application is the acquisition of time-of-flight (TOF) spectra of bunched ions produced in an ion source or ejected from an ion trap. The specifications are the following.

- an NI-FPGA (like PCI 7811R) is required
- FPGA is clocked with 80MHz enabling counting with up to 40MHz.
- the digial IO (TTL) of the FPGA is used -> analog signals as from micro channel plates or channeltrons have to be conditioned by, as an example, using appropriate NIM electronics. Required are pulses with minimum 12.5 ns HIGH and 12.5ns separation between two subsequent pulses.
- the width of a bin in the TOF spectrum is a multiple of 25ns.
- multiple triggering is supported. However, for safe operation the product of the number of re-triggers and number of bins in the TOF spectrum should not exceed 16383.

The interface to the FPGA is encapsulated in an instrument driver which allows to switch betweeen different FPGA targets in the LabVIEW development system. For CS, a dedicated class uses the FPGA instrument driver. The CS class and the instrument driver have been checked into the Subversion repository and are published as package CSNIFPGA-MCS on SourceForge.

Best Regards,

         Dietrich


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Dietrich BECK 
GSI-Darmstadt/EE
email: d....@gs...
tel(fax): +49 6159 71 2520(2986) 
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