diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index b76a7e23e21aecc99b548a542fdaf5155e5a2125..df4c9a8c05fbcd8326a0c82842578d7eb9c1418c 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -290,7 +290,7 @@ class OhmPiHardware:
         ax[0].set_ylabel('Iab [mA]')
         ax[1].plot(self.readings[:, 0], self.readings[:, 2] * self.readings[:, 4], '-b', marker='.', label='vmn')
         ax[1].set_ylabel('Vmn [mV]')
-        ax[2].plot(self.readings[:, 0], self.readings[:, 1], '-g', marker='.', label='pulse')
+        ax[2].plot(self.readings[:, 0], self.readings[:, 2], '-g', marker='.', label='polarity')
         ax[2].set_ylabel('polarity [-]')
         fig.legend()
         plt.show()