diff --git a/components/net/freemodbus/modbus/functions/mbfunccoils_m.c b/components/net/freemodbus/modbus/functions/mbfunccoils_m.c
index f6bb51cdf6..93801de06f 100644
--- a/components/net/freemodbus/modbus/functions/mbfunccoils_m.c
+++ b/components/net/freemodbus/modbus/functions/mbfunccoils_m.c
@@ -196,7 +196,7 @@ eMBMasterReqWriteCoil( UCHAR ucSndAddr, USHORT usCoilAddr, USHORT usCoilData, LO
     UCHAR                 *ucMBFrame;
     eMBMasterReqErrCode    eErrStatus = MB_MRE_NO_ERR;
 
-    if ( usCoilAddr > MB_MASTER_TOTAL_SLAVE_NUM ) eErrStatus = MB_MRE_ILL_ARG;
+    if ( ucSndAddr > MB_MASTER_TOTAL_SLAVE_NUM ) eErrStatus = MB_MRE_ILL_ARG;
     else if ( ( usCoilData != 0xFF00 ) && ( usCoilData != 0x0000 ) ) eErrStatus = MB_MRE_ILL_ARG;
     else if ( xMBMasterRunResTake( lTimeOut ) == FALSE ) eErrStatus = MB_MRE_MASTER_BUSY;
     else
diff --git a/components/net/freemodbus/modbus/functions/mbfuncholding.c b/components/net/freemodbus/modbus/functions/mbfuncholding.c
index e74a0624dc..7921302f96 100644
--- a/components/net/freemodbus/modbus/functions/mbfuncholding.c
+++ b/components/net/freemodbus/modbus/functions/mbfuncholding.c
@@ -183,7 +183,7 @@ eMBFuncReadHoldingRegister( UCHAR * pucFrame, USHORT * usLen )
         usRegAddress++;
 
         usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF] << 8 );
-        usRegCount = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1] );
+        usRegCount |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1] );
 
         /* Check if the number of registers to read is valid. If not
          * return Modbus illegal data value exception. 
diff --git a/components/net/freemodbus/port/portserial.c b/components/net/freemodbus/port/portserial.c
index 317c7f4605..11173579ad 100644
--- a/components/net/freemodbus/port/portserial.c
+++ b/components/net/freemodbus/port/portserial.c
@@ -99,14 +99,14 @@ BOOL xMBPortSerialInit(UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits,
     serial->ops->configure(serial, &(serial->config));
 
     /* open serial device */
-    if (!serial->parent.open(&serial->parent,
-            RT_DEVICE_OFLAG_RDWR | RT_DEVICE_FLAG_INT_RX )) {
-        serial->parent.rx_indicate = serial_rx_ind;
+    if (!rt_device_open(&serial->parent, RT_DEVICE_OFLAG_RDWR | RT_DEVICE_FLAG_INT_RX)) {
+        rt_device_set_rx_indicate(&serial->parent, serial_rx_ind);
     } else {
         return FALSE;
     }
 
     /* software initialize */
+    rt_event_init(&event_serial, "slave event", RT_IPC_FLAG_PRIO);
     rt_thread_init(&thread_serial_soft_trans_irq,
                    "slave trans",
                    serial_soft_trans_irq,
@@ -115,7 +115,6 @@ BOOL xMBPortSerialInit(UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits,
                    sizeof(serial_soft_trans_irq_stack),
                    10, 5);
     rt_thread_startup(&thread_serial_soft_trans_irq);
-    rt_event_init(&event_serial, "slave event", RT_IPC_FLAG_PRIO);
 
     return TRUE;
 }
diff --git a/components/net/freemodbus/port/portserial_m.c b/components/net/freemodbus/port/portserial_m.c
index 8ec0d081f1..366dc79983 100644
--- a/components/net/freemodbus/port/portserial_m.c
+++ b/components/net/freemodbus/port/portserial_m.c
@@ -36,7 +36,7 @@ static rt_uint8_t serial_soft_trans_irq_stack[512];
 static struct rt_thread thread_serial_soft_trans_irq;
 /* serial event */
 static struct rt_event event_serial;
-/* modbus slave serial device */
+/* modbus master serial device */
 static rt_serial_t *serial;
 
 /* ----------------------- Defines ------------------------------------------*/
@@ -100,23 +100,22 @@ BOOL xMBMasterPortSerialInit(UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits,
     serial->ops->configure(serial, &(serial->config));
 
     /* open serial device */
-    if (!serial->parent.open(&serial->parent,
-            RT_DEVICE_OFLAG_RDWR | RT_DEVICE_FLAG_INT_RX )) {
-        serial->parent.rx_indicate = serial_rx_ind;
+    if (!rt_device_open(&serial->parent, RT_DEVICE_OFLAG_RDWR | RT_DEVICE_FLAG_INT_RX)) {
+        rt_device_set_rx_indicate(&serial->parent, serial_rx_ind);
     } else {
         return FALSE;
     }
 
     /* software initialize */
+    rt_event_init(&event_serial, "master event", RT_IPC_FLAG_PRIO);
     rt_thread_init(&thread_serial_soft_trans_irq,
-                   "slave trans",
+                   "master trans",
                    serial_soft_trans_irq,
                    RT_NULL,
                    serial_soft_trans_irq_stack,
                    sizeof(serial_soft_trans_irq_stack),
                    10, 5);
     rt_thread_startup(&thread_serial_soft_trans_irq);
-    rt_event_init(&event_serial, "slave event", RT_IPC_FLAG_PRIO);
 
     return TRUE;
 }
diff --git a/components/net/freemodbus/port/porttimer.c b/components/net/freemodbus/port/porttimer.c
index 6f017d8759..8c51ad06d5 100644
--- a/components/net/freemodbus/port/porttimer.c
+++ b/components/net/freemodbus/port/porttimer.c
@@ -37,7 +37,7 @@ BOOL xMBPortTimersInit(USHORT usTim1Timerout50us)
     rt_timer_init(&timer, "slave timer",
                    timer_timeout_ind, /* bind timeout callback function */
                    RT_NULL,
-                   (50*usTim1Timerout50us)/(1000*1000/RT_TICK_PER_SECOND),
+                   (50 * usTim1Timerout50us) / (1000 * 1000 / RT_TICK_PER_SECOND) + 1,
                    RT_TIMER_FLAG_ONE_SHOT); /* one shot */
     return TRUE;
 }
diff --git a/components/net/freemodbus/port/porttimer_m.c b/components/net/freemodbus/port/porttimer_m.c
index 00441bfd1c..ebf80004d8 100644
--- a/components/net/freemodbus/port/porttimer_m.c
+++ b/components/net/freemodbus/port/porttimer_m.c
@@ -46,7 +46,7 @@ BOOL xMBMasterPortTimersInit(USHORT usTimeOut50us)
     rt_timer_init(&timer, "master timer",
                    timer_timeout_ind, /* bind timeout callback function */
                    RT_NULL,
-                   (50 * usT35TimeOut50us) / (1000 * 1000 / RT_TICK_PER_SECOND),
+                   (50 * usT35TimeOut50us) / (1000 * 1000 / RT_TICK_PER_SECOND) + 1,
                    RT_TIMER_FLAG_ONE_SHOT); /* one shot */
 
     return TRUE;