diff --git a/sw/include/tester.h b/sw/include/tester.h
new file mode 100644
index 0000000..b92edb6
--- /dev/null
+++ b/sw/include/tester.h
@@ -0,0 +1,6 @@
+#ifndef TESTER_H__
+#define TESTER_H__
+
+void tester_poll(void);
+
+#endif /* TESTER_H__ */
\ No newline at end of file
diff --git a/sw/include/usb-cdc.h b/sw/include/usb-cdc.h
index 20b7836..63b2b9e 100644
--- a/sw/include/usb-cdc.h
+++ b/sw/include/usb-cdc.h
@@ -38,6 +38,8 @@ LGPL License Terms @ref lgpl_license
 #ifndef __CDC_H
 #define __CDC_H
 
+#include <stdint.h>
+
 /* Definitions of Communications Device Class from
  * "Universal Serial Bus Class Definitions for Communications Devices
  * Revision 1.2"
@@ -156,6 +158,9 @@ struct usb_cdc_notification {
 	uint16_t wLength;
 } __attribute__((packed));
 
+int cdc_connected();
+void cdc_set_connected(int is_connected);
+
 #endif
 
 /**@}*/
diff --git a/sw/src/main.c b/sw/src/main.c
index c191409..9e9802e 100644
--- a/sw/src/main.c
+++ b/sw/src/main.c
@@ -41,6 +41,9 @@ int main(int argc, char **argv)
     while (1)
     {
         usb_poll();
+        if (cdc_connected()) {
+            tester_poll();
+        }
     }
     return 0;
 }
diff --git a/sw/src/tester.c b/sw/src/tester.c
new file mode 100644
index 0000000..6350a15
--- /dev/null
+++ b/sw/src/tester.c
@@ -0,0 +1,5 @@
+#include <tester.h>
+
+void tester_poll(void) {
+    return;
+}
\ No newline at end of file
diff --git a/sw/src/usb-cdc.c b/sw/src/usb-cdc.c
new file mode 100644
index 0000000..52d511c
--- /dev/null
+++ b/sw/src/usb-cdc.c
@@ -0,0 +1,13 @@
+#include <usb-cdc.h>
+
+static int connected = 0;
+
+int cdc_connected(void)
+{
+    return connected;
+}
+
+void cdc_set_connected(int is_connected)
+{
+    connected = is_connected;
+}
\ No newline at end of file
diff --git a/sw/src/usb-setup.c b/sw/src/usb-setup.c
index 5ca3160..59e76b3 100644
--- a/sw/src/usb-setup.c
+++ b/sw/src/usb-setup.c
@@ -3,6 +3,7 @@
 #include <usb.h>
 
 #include <usb-desc.h>
+#include <usb-cdc.h>
 
 static uint8_t reply_buffer[8];
 static uint8_t usb_configuration = 0;
@@ -15,6 +16,14 @@ void usb_setup(const struct usb_setup_request *setup)
 
     switch (setup->wRequestAndType)
     {
+
+    case 0x2021: // Set Line Coding
+        break;
+
+    case 0x2221: // Set control line state
+        cdc_set_connected(setup->wValue & 1); /* Check RTS bit */
+        break;
+
     case 0x0500: // SET_ADDRESS
     case 0x0b01: // SET_INTERFACE
         break;