safety net for better scope trace grab protection

1 files changed, 14 insertions, 7 deletions

diff --git a/qolab/hardware/scope/sds1104x.py b/qolab/hardware/scope/sds1104x.py
index 493be48..657f599 100644
--- a/qolab/hardware/scope/sds1104x.py
+++ b/qolab/hardware/scope/sds1104x.py
@@ -104,14 +104,21 @@ class SDS1104X(ScopeSCPI):
             #   FP = 1 corresponds to the second data point
         self.write(cstr)
 
+        trRaw = Trace(f'Ch{chNum}')
+
         qstr = f'C{chNum}:WAVEFORM? DAT2'
-        wfRaw=self.query_binary_values(qstr, datatype='b', header_fmt='ieee', container=np.array, chunk_size=(Npnts+100)) 
         # expected full reply: 'C1:WF DAT2,#9000000140.........'
-        trRaw = Trace(f'Ch{chNum}')
-        trRaw.values = wfRaw.reshape(wfRaw.size,1)
-        if decimate and sparsing != 1:
-            numtaps = 3; # not sure it is the best case
-            trRaw.values = scipy.signal.decimate(trRaw.values, sparsing, 3, axis=0)
+        try:
+            wfRaw=self.query_binary_values(qstr, datatype='b', header_fmt='ieee', container=np.array, chunk_size=(Npnts+100)) 
+            trRaw.values = wfRaw.reshape(wfRaw.size,1)
+            if decimate and sparsing != 1:
+                numtaps = 3; # not sure it is the best case
+                trRaw.values = scipy.signal.decimate(trRaw.values, sparsing, 3, axis=0)
+        except ValueError as err:
+            # most likely we get crazy number of points
+            # self.read() # flushing the bogus output of previous command
+            print(f'Error: getting waveform failed for {qstr=}')
+            wfRaw=np.array([])
         trRaw.config['unit'] = 'Count'
         trRaw.config['tags']['Decimate'] = decimate
         return(trRaw, availableNpnts, Npnts)
@@ -226,7 +233,7 @@ if __name__ == '__main__':
     instr=rm.open_resource('TCPIP::192.168.0.62::INSTR')
     scope = SDS1104X(instr)
     print(f'ID: {scope.idn}')
-    print(f'Ch1 mean: {scope.mean(1)}')
+    # print(f'Ch1 mean: {scope.mean(1)}')
     print(f'Ch1 available points: {scope.getAvailableNumberOfPoints(1)}')
     print(f'Sample Rate: {scope.getSampleRate()}')
     print(f'Time per Div: {scope.getTimePerDiv()}')