diff --git a/IOB-WIN-NEXT/IobSiemensRobotService.cs b/IOB-WIN-NEXT/IobSiemensRobotService.cs
index 194026fe..069979c5 100644
--- a/IOB-WIN-NEXT/IobSiemensRobotService.cs
+++ b/IOB-WIN-NEXT/IobSiemensRobotService.cs
@@ -88,7 +88,11 @@ namespace IOB_WIN_NEXT
             // bit 0 (poweron) imposto a 1 SE connected...
             if (currPLC.IsConnected)
             {
-                byteSignals += (1 << 0);
+                byteSignals |= (1 << 0);
+            }
+            else
+            {
+                byteSignals &= ~(1 << 0);
             }
 
             // salvo!