diff --git a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiActuatorBase.java b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiActuatorBase.java
index a94b2c7..e36a58f 100644
--- a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiActuatorBase.java
+++ b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiActuatorBase.java
@@ -112,7 +112,7 @@ abstract public class DiActuatorBase implements DiActuator {
     }
 
     // execute device command
-    protected DiCommandResponse call( DiCommand cmd, Object... args ) {
+    synchronized protected DiCommandResponse call( DiCommand cmd, Object... args ) {
         return this.device.call(cmd, this.mid, args);
     }