diff --git a/cube/User/Src/mbusComm.c b/cube/User/Src/mbusComm.c
index 288d8f9..50f07d9 100644
--- a/cube/User/Src/mbusComm.c
+++ b/cube/User/Src/mbusComm.c
@@ -56,28 +56,20 @@ static void handleRequestEngine(void *handle) {
             loopEnable();
             schAdd(handleRequestEngine, handle, 10, 0); // give 10ms to settled the loop
         } else {
-            // write(fd, sendBuf, 5);
             localMbusCommHandle->retryCnt = 0;
             HAL_UART_Transmit_IT(&mbusUart, localMbusCommHandle->sendBuf, 5);
             localMbusCommHandle->state = SENDING;
-            // schAdd(handleRequestEngine, handle, 15, 0);  // ask me again in 15ms in the next state ...
         }
         break;
 
+        // transition from SENDING to SENDING_DONE is initiate by mbusCommTxCpltCallback
+        // interrupt callback
         case SENDING:
         logMsg("hre state SENDING");
         break;
 
         case SENDING_DONE:
         logMsg("hre state SENDING_DONE");
-        /*
-        if (HAL_UART_GetState(&mbusUart) == HAL_UART_STATE_READY) { // ... whether I'm done
-            localMbusCommHandle->state = ENABLE_FRONTEND;
-            schAdd(handleRequestEngine, handle, 3, 0);
-        } else {
-            schAdd(handleRequestEngine, handle, 1, 0); // not yet done, ask me again in 1ms
-        }
-        */
         localMbusCommHandle->state = ENABLE_FRONTEND;
         schAdd(handleRequestEngine, handle, 3, 0);
         break;