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<p>Dear friends,</p>
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<p>were found some unexpected (at least to us) behaviour when looking at the JSON output from UCESB.</p>
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<p>We are using the following command to generate the JSON outout:</p>
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<div><span style="font-size:10pt">../../ucesb/jena_polarimeter/jena_polarimeter stream://localhost:8003 --ntuple=UNPACK,STRUCT,- | ../../ucesb/hbook/struct_writer - --dump=compact_json</span></div>
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<p></p>
<p>In our DAQ, there are sitting CAEN V785 modules. The *.spec file for these modules looks like this:</p>
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<div><span style="font-size:10pt">#define VME_CAEN_V792 VME_CAEN_V775</span><br>
<span style="font-size:10pt">#define VME_CAEN_V785 VME_CAEN_V775</span><br>
<br>
<span style="font-size:10pt">VME_CAEN_V775(geom,</span><br>
<span style="font-size:10pt"> crate)</span><br>
<span style="font-size:10pt">{</span><br>
<span style="font-size:10pt"> MEMBER(DATA12_OVERFLOW data[32] ZERO_SUPPRESS);</span><br>
<br>
<span style="font-size:10pt"> UINT32 header NOENCODE</span><br>
<span style="font-size:10pt"> {</span><br>
<span style="font-size:10pt"> // 0_7: undefined;</span><br>
<span style="font-size:10pt"> 8_13: count;</span><br>
<span style="font-size:10pt"> 16_23: crate = MATCH(crate);</span><br>
<span style="font-size:10pt"> 24_26: 0b010;</span><br>
<span style="font-size:10pt"> 27_31: geom = MATCH(geom);</span><br>
<span style="font-size:10pt"> }</span><br>
<br>
<span style="font-size:10pt"> list(0<=index<header.count)</span><br>
<span style="font-size:10pt"> {</span><br>
<span style="font-size:10pt"> UINT32 ch_data NOENCODE</span><br>
<span style="font-size:10pt"> {</span><br>
<span style="font-size:10pt"> 0_11: value;</span><br>
<br>
<span style="font-size:10pt"> 12: overflow;</span><br>
<span style="font-size:10pt"> 13: underflow;</span><br>
<span style="font-size:10pt"> 14: valid;</span><br>
<br>
<span style="font-size:10pt"> // 15: undefined;</span><br>
<br>
<span style="font-size:10pt"> 16_20: channel;</span><br>
<br>
<span style="font-size:10pt"> 24_26: 0b000;</span><br>
<span style="font-size:10pt"> 27_31: geom = CHECK(geom);</span><br>
<br>
<span style="font-size:10pt"> ENCODE(data[channel],(value=value,overflow=overflow));</span><br>
<span style="font-size:10pt"> }</span><br>
<span style="font-size:10pt"> }</span><br>
<br>
<span style="font-size:10pt"> UINT32 eob</span><br>
<span style="font-size:10pt"> {</span><br>
<span style="font-size:10pt"> 0_23: event_number;</span><br>
<span style="font-size:10pt"> 24_26: 0b100;</span><br>
<span style="font-size:10pt"> 27_31: geom = CHECK(geom);</span><br>
<span style="font-size:10pt"> // NOENCODE;</span><br>
<span style="font-size:10pt"> }</span><br>
<span style="font-size:10pt">}</span></div>
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<p></p>
<p>Now comes the strange part: from time to time we get values greater than 2^12 in the arrays belonging to the 12-bit ADC data (the values are than usually in the 36xxx ballpark). We assume that these are the overflow events and for some reason they are translated
to values of 2^15 + something in the JSON output data.</p>
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</p>
<p>Is our interprtation correct and if yes, is this intended behaviour?</p>
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</p>
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</p>
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<p>Many thanks!</p>
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<p>Best greetings</p>
<p>Günter<br>
</p>
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