diff --git a/MPSSELight/ftdi/FtdiDevice.cs b/MPSSELight/ftdi/FtdiDevice.cs
index 10d5399..73be8e5 100644
--- a/MPSSELight/ftdi/FtdiDevice.cs
+++ b/MPSSELight/ftdi/FtdiDevice.cs
@@ -43,7 +43,18 @@ private void open(string serialNumber)
                 if (ftStatus == FTDI.FT_STATUS.FT_OK)
                     return;
 
-                String errMsg = "Failed to open device (error " + ftStatus.ToString() + ")";
+                String errMsg = "Failed to open device using serial " + serialNumber + "(error " + ftStatus.ToString() + ")";
+                throw new FtdiException(errMsg);
+            }
+        }
+
+        private void open(uint locId) {
+            lock (_lock) {
+                FTDI.FT_STATUS ftStatus = ftdi.OpenByLocation(locId);
+                if (ftStatus == FTDI.FT_STATUS.FT_OK)
+                    return;
+
+                String errMsg = "Failed to open device using index " + locId + "(error " + ftStatus.ToString() + ")";
                 throw new FtdiException(errMsg);
             }
         }
@@ -138,6 +149,11 @@ public FtdiDevice(string serialNumber)
             open(serialNumber);
         }
 
+        public FtdiDevice(uint locId) {
+            ftdi = new FTDI();
+            open(locId);
+        }
+
         public void Dispose()
         {
             if (ftdi.IsOpen)