diff --git a/src/lib/barrier/HdmiSwitch.cpp b/src/lib/barrier/HdmiSwitch.cpp
new file mode 100644
index 00000000..881e6e7e
--- /dev/null
+++ b/src/lib/barrier/HdmiSwitch.cpp
@@ -0,0 +1,106 @@
+
+#include "HdmiSwitch.h"
+#include "base/Log.h"
+
+static string lastPortSettings("");
+string deviceName;
+int baudRate, dataBits, parity, stopBits;
+static HANDLE comPort = INVALID_HANDLE_VALUE;
+
+void HdmiSwitch::SendCommand(const string & command, const string & portSettings)
+{
+  try
+  {
+    LOG((CLOG_INFO "Sending command to HDMI switch. Command: %s, portSettings: %s", command.c_str(), portSettings.c_str()));
+    if (comPort == INVALID_HANDLE_VALUE || lastPortSettings.compare(portSettings) != 0)
+    {
+      ParsePortSettings(portSettings);
+      OpenComPort();
+    }
+    SendStringToComPort(command);
+  }
+  catch (std::exception & e)
+  {
+    LOG((CLOG_ERR "Unable to send command to HDMI switch: %s", e.what()));
+  }
+}
+
+void HdmiSwitch::ParsePortSettings(const string& portSettings)
+{
+  lastPortSettings = portSettings;
+  if (comPort != INVALID_HANDLE_VALUE) CloseHandle(comPort);
+
+  try
+  {
+    //device name
+    int posB = 0;
+    int posE = portSettings.find('-');
+    string deviceName = string("\\\\.\\") + portSettings.substr(posB, posE - posB);
+
+    //baud rate
+    posB = posE + 1;
+    posE = portSettings.find('-', posB);
+    baudRate = std::stoi(portSettings.substr(posB, posE - posB));
+
+    //data bits
+    posB = posE + 1;
+    dataBits = portSettings[posB] - '0';
+
+    //parity bit
+    posB = posB + 1;
+    const string parityLetters = "NOEMS";
+    parity = parityLetters.find(portSettings[posB]);
+
+    //stop bits
+    posB = posB + 1;
+    posE = portSettings.length() + 1;
+    string stopBitsString = portSettings.substr(posB, posE - posB);
+    stopBits = ONESTOPBIT;
+    if (stopBitsString == "1.5") stopBits = ONE5STOPBITS;
+    else if (stopBitsString == "2") stopBits = TWOSTOPBITS;
+
+    LOG((CLOG_INFO "COM port settings: device '%s'  baud %d  data %d  parity %d  stop %d", deviceName.c_str(), baudRate, dataBits, parity, stopBits));
+  }
+  catch (std::exception& e)
+  {
+    throw std::invalid_argument("Port settings string could not be parsed.");
+  }
+}
+
+void HdmiSwitch::OpenComPort()
+{
+  try
+  {
+    //open com port
+    comPort = CreateFile(deviceName.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
+    if (comPort == INVALID_HANDLE_VALUE) throw std::exception("");
+
+    //set port parameters
+    DCB params = { 0 };
+    params.DCBlength = sizeof(params);
+    if (!GetCommState(comPort, &params)) throw std::exception("");
+    params.BaudRate = baudRate;
+    params.ByteSize = dataBits;
+    params.Parity = parity;
+    params.StopBits = stopBits;
+    if (!SetCommState(comPort, &params)) throw std::exception("");
+
+    //set timeouts
+    COMMTIMEOUTS timeouts = { 50, 10, 50, 10, 50 };
+    if (!SetCommTimeouts(comPort, &timeouts)) throw std::exception("");
+  }
+  catch (std::exception & e)
+  {
+    if (comPort != INVALID_HANDLE_VALUE) CloseHandle(comPort);
+    comPort = INVALID_HANDLE_VALUE;
+    throw std::exception("COM port could not be opened.");
+  }
+}
+
+void HdmiSwitch::SendStringToComPort(const string & command)
+{
+  DWORD bytes_written = 0;
+  if (!WriteFile(comPort, command.c_str(), command.length(), &bytes_written, NULL))
+    throw std::exception("Write to COM port failed.");
+}
+
diff --git a/src/lib/barrier/HdmiSwitch.h b/src/lib/barrier/HdmiSwitch.h
new file mode 100644
index 00000000..2a6411b5
--- /dev/null
+++ b/src/lib/barrier/HdmiSwitch.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <string>
+using std::string;
+
+class HdmiSwitch
+{
+private:
+  static void ParsePortSettings(const string & portSettings);
+  static void OpenComPort();
+  static void SendStringToComPort(const string & command);
+public:
+  static void SendCommand(const string & command, const string & portSettings);
+};
diff --git a/src/lib/server/Server.cpp b/src/lib/server/Server.cpp
index 334049cf..1091f90e 100644
--- a/src/lib/server/Server.cpp
+++ b/src/lib/server/Server.cpp
@@ -43,6 +43,7 @@
 #include "base/IEventQueue.h"
 #include "base/Log.h"
 #include "base/TMethodEventJob.h"
+#include "barrier/HdmiSwitch.h"
 
 #include <cstring>
 #include <cstdlib>
@@ -523,6 +524,13 @@ Server::switchScreen(BaseClientProxy* dst,
 	else {
 		m_active->mouseMove(x, y);
 	}
+
+	//TODO: make command and portSettings editable, e.g., in ScreenSettingsDialog
+	const std::string & command = (dst == m_primaryClient) ? "port0R" : "port1R";
+	const std::string & portSettings = "COM4-9600-8N1";
+	
+	if (!command.empty() && !portSettings.empty())
+	  HdmiSwitch::SendCommand(command, portSettings);
 }
 
 void