Added check if sweep has positive steps (to be checked if this limitation is true).

TimeBaseAOMDriver/labscript_devices.py

@@ -78,6 +78,9 @@ class TimeBaseFreqSweepTrigger(DigitalOut):
             raise LabscriptError(f"Ramp mode of device {self.name} for frequency sweep can only be 2 (triangle) or 4 (sawtooth).")
         if not initial == self.AOM.freq.static_value:
             raise LabscriptError(f"Start frequency {initial} of {self.name} must be equal to AOM freuquency ({self.AOM.freq.static_value})")
+        if initial>final:
+            # TODO check downward sawtooth ramps
+            raise LabscriptError("TimeBase Trigger only supports positive frequency steps! Use FM or triangle mode.")
         # Set TimeBase sweep parameters
         self.start_freq.constant(initial)
         self.stop_freq.constant(final)