diff --git a/MainCode/adalm1000_logger.py b/MainCode/adalm1000_logger.py
index 2fa3d24..b35d172 100644
--- a/MainCode/adalm1000_logger.py
+++ b/MainCode/adalm1000_logger.py
@@ -2365,11 +2365,12 @@ class BatteryTester(QMainWindow):
 
     def auto_scale_axes(self):
         """Auto-scale plot axes with appropriate padding and strict boundaries"""
-        if not self.time_data:
+        if not self.active_device or not self.active_device.time_data:
             return
         
+        dev = self.active_device
         min_time = 0
-        max_time = self.time_data[-1]
+        max_time = dev.time_data[-1]
         current_xlim = self.ax.get_xlim()
         
         if max_time > current_xlim[1] * 0.95:
@@ -2378,17 +2379,17 @@ class BatteryTester(QMainWindow):
             self.ax2.set_xlim(min_time, new_max)
         
         voltage_padding = 0.2
-        if self.voltage_data:
-            min_voltage = max(0, min(self.voltage_data) - voltage_padding)
-            max_voltage = min(5.0, max(self.voltage_data) + voltage_padding)
+        if dev.voltage_data:
+            min_voltage = max(0, min(dev.voltage_data) - voltage_padding)
+            max_voltage = min(5.0, max(dev.voltage_data) + voltage_padding)
             current_ylim = self.ax.get_ylim()
             if (abs(current_ylim[0] - min_voltage) > 0.1 or abs(current_ylim[1] - max_voltage) > 0.1):
                 self.ax.set_ylim(min_voltage, max_voltage)
         
         current_padding = 0.05
-        if self.current_data:
-            min_current = max(-0.25, min(self.current_data) - current_padding)
-            max_current = min(0.25, max(self.current_data) + current_padding)
+        if dev.current_data:
+            min_current = max(-0.25, min(dev.current_data) - current_padding)
+            max_current = min(0.25, max(dev.current_data) + current_padding)
             current_ylim2 = self.ax2.get_ylim()
             if (abs(current_ylim2[0] - min_current) > 0.02 or abs(current_ylim2[1] - max_current) > 0.02):
                 self.ax2.set_ylim(min_current, max_current)