diff --git a/script/Marco/power-supply.py b/script/Marco/power-supply.py
index 946474d..7629a9a 100644
--- a/script/Marco/power-supply.py
+++ b/script/Marco/power-supply.py
@@ -61,7 +61,7 @@ ActualVA.close()
 ActualIA.close()
 
 readable =    detector2
-positions =   scan.positions(0)
+positions =   scan.writables(0)
 
 threshold = (min(readable) + max(readable))/2
 min_peak_distance = 5.0