diff --git a/freemodbus-v1.6/mbrtu.c b/freemodbus-v1.6/mbrtu.c
index 0e7c9fd5bd58a19912ebeb1e177fba36c0be4c8c..b1b5813c05256a227ed0018772d70e381c42a19e 100644
--- a/freemodbus-v1.6/mbrtu.c
+++ b/freemodbus-v1.6/mbrtu.c
@@ -197,6 +197,11 @@ eMBRTUSend(  MBTypeDef* psModbus, UCHAR ucSlaveAddress, const UCHAR * pucFrame,
 
         /* Activate the transmitter. */
         psModbus->eSndState = STATE_TX_XMIT;
+        //启动第一次发送，这样才可以进入发送完成中断
+        psModbus->xMBPortSerialPutByte( ( CHAR )*psModbus->pucSndBufferCur );
+        psModbus->pucSndBufferCur++;  /* next byte in sendbuffer. */
+        psModbus->usSndBufferCount--;
+		//使能发送状态，禁止接收状态
         psModbus->vMBPortSerialEnable( FALSE, TRUE );
     }
     else