diff --git a/NanoVNASaver/Hardware/NanoVNA.py b/NanoVNASaver/Hardware/NanoVNA.py
index cf46e83..f165af0 100644
--- a/NanoVNASaver/Hardware/NanoVNA.py
+++ b/NanoVNASaver/Hardware/NanoVNA.py
@@ -40,25 +40,24 @@ class NanoVNA(VNA):
         super().__init__(iface)
         version_string = self.readVersion()
         self.version = Version(version_string)
+        self.sweep_method = "sweep"
+        self.start = 27000000
+        self.stop = 30000000
+        self._sweepdata = []
 
-        logger.debug("Testing against 0.2.0")
-        if version_string.find("extended with scan") > 0:
-            logger.debug("Incompatible scan command detected.")
-            self.features.add("Incompatible scan command")
-            self.useScan = False
+        if self.version >= Version("0.7.1"):
+            self.features.add("Scan mask command")
+            self.sweep_method = "scan_mask"
         elif self.version >= Version("0.2.0"):
             logger.debug("Newer than 0.2.0, using new scan command.")
-            self.features.add("New scan command")
-            self.useScan = True
-        else:
-            logger.debug("Older than 0.2.0, using old sweep command.")
-            self.features.add("Original sweep method")
-            self.useScan = False
+            self.features.add("Scan command")
+            self.sweep_method = "scan"
         self.readFeatures()
 
     def isValid(self):
         return True
 
+
     def _capture_data(self) -> bytes:
         with self.serial.lock:
             drain_serial(self.serial)
@@ -101,8 +100,49 @@ class NanoVNA(VNA):
         self.writeSerial("resume")
 
     def setSweep(self, start, stop):
-        if self.useScan:
-            self.writeSerial(f"scan {start} {stop} {self.datapoints}")
-        else:
+        self.start = start
+        self.stop = stop
+        if self.sweep_method == "sweep":
             self.writeSerial(f"sweep {start} {stop} {self.datapoints}")
-            sleep(1)
+        elif self.sweep_method == "scan":
+            self.writeSerial(f"scan {start} {stop} {self.datapoints}")
+
+    def readFrequencies(self) -> List[int]:
+        if self.sweep_method != "scan_mask":
+            return super().readFrequencies()
+        step = (self.stop - self.start) / (self.datapoints - 1.0)
+        return [round(self.start + i * step) for i in range(self.datapoints)]
+
+    def readValues(self, value) -> List[str]:
+        if self.sweep_method != "scan_mask":
+            return super().readValues(value)
+        logger.debug("readValue with scan mask (%s)", value)
+        # Actually grab the data only when requesting channel 0.
+        # The hardware will return all channels which we will store.
+        if value == "data 0":
+            self._sweepdata = []
+            try:
+                with self.serial.lock:
+                    drain_serial(self.serial)
+                    self.serial.write(
+                        (f"scan {self.start} {self.stop}"
+                         f' {self.datapoints} 0b110\r'
+                         ).encode("ascii"))
+                    self.serial.readline()
+                    sleep(0.6)
+                    logger.info("reading values")
+                    for line in self.serial.readlines():
+                        line = line.decode("ascii").strip()
+                        if line.startswith("ch>"):
+                            break
+                        logger.debug("Line: %s", line)
+                        data = line.split()
+                        self._sweepdata.append((
+                            f"{data[0]} {data[1]}",
+                            f"{data[2]} {data[3]}"))
+            except IOError as exc:
+                logger.error("Error readValues: %s", exc)
+        if value == "data 0":
+            return [x[0] for x in self._sweepdata]
+        if value == "data 1":
+            return [x[1] for x in self._sweepdata]
diff --git a/NanoVNASaver/Hardware/NanoVNA_V2.py b/NanoVNASaver/Hardware/NanoVNA_V2.py
index dc323d1..bbea8e5 100644
--- a/NanoVNASaver/Hardware/NanoVNA_V2.py
+++ b/NanoVNASaver/Hardware/NanoVNA_V2.py
@@ -77,7 +77,7 @@ class NanoVNAV2(VNA):
         self.features.add("Multi data points")
 
         # firmware major version of 0xff indicates dfu mode
-        if self.firmware.major == 0xff:
+        if self.firmware.data["major"] == 0xff:
             raise IOError('Device is in DFU mode')
 
         self.sweepStartHz = 200e6
diff --git a/NanoVNASaver/NanoVNASaver.py b/NanoVNASaver/NanoVNASaver.py
index efcc776..c38c2f5 100644
--- a/NanoVNASaver/NanoVNASaver.py
+++ b/NanoVNASaver/NanoVNASaver.py
@@ -25,7 +25,6 @@ from time import sleep, strftime, localtime
 from typing import List
 
 from PyQt5 import QtWidgets, QtCore, QtGui
-from serial import SerialException
 
 from .Windows import (
     AboutWindow, AnalysisWindow, CalibrationWindow,
@@ -617,14 +616,12 @@ class NanoVNASaver(QtWidgets.QWidget):
             if not self.interface.isOpen():
                 logger.error("Unable to open port %s", self.interface)
                 return
- 
-        sleep(0.05)
-
+        sleep(0.1)
         try:
             self.vna = get_VNA(self.interface)
         except IOError as exc:
             logger.error("Unable to connect to VNA: %s", exc)
-            
+
         self.vna.validateInput = self.settings.value("SerialInputValidation", True, bool)
         self.worker.setVNA(self.vna)