diff --git a/QGL/drivers/APS2Pattern.py b/QGL/drivers/APS2Pattern.py
index 7a54251b..224d1158 100644
--- a/QGL/drivers/APS2Pattern.py
+++ b/QGL/drivers/APS2Pattern.py
@@ -1390,8 +1390,9 @@ def tdm_instructions(seqs):
 
             elif isinstance(s, PulseSequencer.Pulse):
                 if s.label == 'MEAS' and s.maddr != (-1, 0):
+                    # tdm_chan specifies the input channel to the TDM carrying the qubit state. Defaults to 1
                     tdm_chan = m.channel.processor_chan.channel if getattr(m.channel, 'processor_chan') else 1
-                    instructions.append(CrossBar(2**m.maddr[1], 2**(tdm_chan-1)))
+                    instructions.append(CrossBar(2**m.maddr[1], 2**(tdm_chan-1)), label=label)
                     instructions.append(LoadCmp(label=label))
                     instructions.append(StoreMeas(s.maddr[0], 1 << 16, label=label))
 
@@ -1405,6 +1406,7 @@ def tdm_instructions(seqs):
                     if len(set(maddr))>1:
                         raise Exception('Storing simultaneous measurements on different addresses not supported.')
                     for n,m in enumerate(sim_meas):
+                        # each tdm_chan specifies the input channel to the TDM carrying the corresponding qubit state. Default values  are the first n channels
                         tdm_chan = m.channel.processor_chan.channel if getattr(m.channel, 'processor_chan') else n+1
                         instructions.append(CrossBar(2**m.maddr[1], 2**(tdm_chan-1)))
                     instructions.append(LoadCmp(label=label))