diff --git a/examples/device/cdc_dual_ports/src/main.c b/examples/device/cdc_dual_ports/src/main.c
index 813639179..d6e38df85 100644
--- a/examples/device/cdc_dual_ports/src/main.c
+++ b/examples/device/cdc_dual_ports/src/main.c
@@ -83,15 +83,18 @@ static void cdc_task(void)
 
   for (itf = 0; itf < CFG_TUD_CDC; itf++)
   {
-    if ( tud_cdc_n_available(itf) )
+    if ( tud_cdc_n_connected(itf) )
     {
-      uint8_t buf[64];
+      if ( tud_cdc_n_available(itf) )
+      {
+        uint8_t buf[64];
 
-      uint32_t count = tud_cdc_n_read(itf, buf, sizeof(buf));
+        uint32_t count = tud_cdc_n_read(itf, buf, sizeof(buf));
 
-      // echo back to both serial ports
-      echo_serial_port(0, buf, count);
-      echo_serial_port(1, buf, count);
+        // echo back to both serial ports
+        echo_serial_port(0, buf, count);
+        echo_serial_port(1, buf, count);
+      }
     }
   }
 }
diff --git a/examples/device/cdc_msc/src/main.c b/examples/device/cdc_msc/src/main.c
index bcf05eaac..a407e2ddd 100644
--- a/examples/device/cdc_msc/src/main.c
+++ b/examples/device/cdc_msc/src/main.c
@@ -105,31 +105,34 @@ void tud_resume_cb(void)
 //--------------------------------------------------------------------+
 void cdc_task(void)
 {
-  // is data available to read from rx fifo
-  if ( tud_cdc_available() )
+  if ( tud_cdc_connected() )
   {
-    uint8_t buf[64];
-
-    // read and echo back
-    uint32_t count = tud_cdc_read(buf, sizeof(buf));
-
-    for(uint32_t i=0; i<count; i++)
+    // connected and there are data available
+    if ( tud_cdc_available() )
     {
-      tud_cdc_write_char(buf[i]);
+      uint8_t buf[64];
 
-      if ( buf[i] == '\r' ) tud_cdc_write_char('\n');
+      // read and echo back
+      uint32_t count = tud_cdc_read(buf, sizeof(buf));
+
+      for(uint32_t i=0; i<count; i++)
+      {
+        tud_cdc_write_char(buf[i]);
+
+        if ( buf[i] == '\r' ) tud_cdc_write_char('\n');
+      }
+
+      tud_cdc_write_flush();
     }
-
-    tud_cdc_write_flush();
   }
 }
 
-// Invoked when cdc line state changed e.g connected/disconnected
+// Invoked when cdc when line state changed e.g connected/disconnected
 void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts)
 {
   (void) itf;
 
-  // usually terminal software sets DTR and RTS when connected
+  // connected
   if ( dtr && rts )
   {
     // print initial message when connected
diff --git a/examples/device/cdc_msc_freertos/src/main.c b/examples/device/cdc_msc_freertos/src/main.c
index 712255880..1371b84c3 100644
--- a/examples/device/cdc_msc_freertos/src/main.c
+++ b/examples/device/cdc_msc_freertos/src/main.c
@@ -168,22 +168,25 @@ void cdc_task(void* params)
   // RTOS forever loop
   while ( 1 )
   {
-    // is data available to read from rx fifo
-    if ( tud_cdc_available() )
+    if ( tud_cdc_connected() )
     {
-      uint8_t buf[64];
-
-      // read and echo back
-      uint32_t count = tud_cdc_read(buf, sizeof(buf));
-
-      for(uint32_t i=0; i<count; i++)
+      // connected and there are data available
+      if ( tud_cdc_available() )
       {
-        tud_cdc_write_char(buf[i]);
+        uint8_t buf[64];
 
-        if ( buf[i] == '\r' ) tud_cdc_write_char('\n');
+        // read and echo back
+        uint32_t count = tud_cdc_read(buf, sizeof(buf));
+
+        for(uint32_t i=0; i<count; i++)
+        {
+          tud_cdc_write_char(buf[i]);
+
+          if ( buf[i] == '\r' ) tud_cdc_write_char('\n');
+        }
+
+        tud_cdc_write_flush();
       }
-
-      tud_cdc_write_flush();
     }
 
     // For ESP32-S2 this delay is essential to allow idle how to run and reset wdt
@@ -191,12 +194,12 @@ void cdc_task(void* params)
   }
 }
 
-// Invoked when cdc line state changed e.g connected/disconnected
+// Invoked when cdc when line state changed e.g connected/disconnected
 void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts)
 {
   (void) itf;
 
-  // usually terminal software sets DTR and RTS when connected
+  // connected
   if ( dtr && rts )
   {
     // print initial message when connected