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Entry  Wed Jan 6 15:51:58 2016, Larry Byars, Use of Channel Cascading in drs_exam.cpp 
    Reply  Tue Jan 12 15:42:31 2016, Larry Byars, Use of Channel Cascading in drs_exam.cpp 
       Reply  Tue Jan 12 16:06:07 2016, Stefan Ritt, Use of Channel Cascading in drs_exam.cpp 
Message ID: 470     Entry time: Tue Jan 12 16:06:07 2016     In reply to: 469
Author: Stefan Ritt 
Subject: Use of Channel Cascading in drs_exam.cpp 

Hi Larry,

sorry my late reply, swamped with work here. You were right in the modifictions you did, congrats. The speed limitation of 500 events come from USB2, which simply is not fast enough. The 500 Hz are mentioned on the evaluation board web site, so you should have seen that before ordering. Some people build their own hardware around the chip, in which case they get higher rates. The "hard" limit is the DRS4 readout speed, which is 30ns per sample. So if you have 8 ADCs in parallel, and you only need 100 samples of your waveform, the readout time is 3 us, in which case you could go up to a few 10 kHz without much of a dead time.


Larry Byars wrote:

An update. I have been successful in making modifications to drs_exam.cpp so that I can get 2048 samples per channel.. The main changes were to the size of the time_array and wave_array and adding a call to Set ChannelConfig(0,8,4). It was also necessary to change the parameters to GetWave so that the Trigger Cell and WSR values were passed to get the channel combinations correct (2048 channel.ppt).

I've moved on to try to increase the speed of acquisition (I get only about 500 events/sec) and trying to understand the corrections.Working through the source code slowly...


Larry Byars

Larry Byars wrote:

Hello Stefan,

Here in Rockford, TN we just got a new DRS4 evaluation board (Serail # 2612, Board Type 9, Firmware 21305) which is labeled as combined 2048.

It looks like the drs_exam.cpp only works with 1024 samples per channel. We'd like to be able to get 2048 samples from each of the four channels but I am uncertain what code modifications are necessary support this.

Could you offer a suggestion? I've searched the forum for cascade and read several threads but they are pretty old. One even says it isn't supported in the evaluation board, but I think that is no longer the case.


Thanks for your help,


Larry Byars




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