fixed hardcoded max_instructions in error message

Author: ReneKolb

PulseBlaster.py

@@ -509,7 +509,7 @@ def convert_to_pb_inst(self, dig_outputs, dds_outputs, freqs, amps, phases):
             raise AssertionError('Invalid programming scheme %s'%str(self.programming_scheme))
 
         if len(pb_inst) > self.max_instructions:
-            raise LabscriptError("The Pulseblaster memory cannot store more than 4000 instuctions, but the PulseProgram contains {:d} instructions.".format(len(pb_inst))) 
+            raise LabscriptError("The Pulseblaster memory cannot store more than {:d} instuctions, but the PulseProgram contains {:d} instructions.".format(self.max_instructions, len(pb_inst))) 
 
         return pb_inst