The semaphore timeout period has expired error for USB connection

Question

I m getting this error        The semaphore timeout period has expired    On this line        ThePorts ActivePort1 Open         but I only get it from time to time  When it happens  it happens over and over again  Then the problem goes away  for hours or days  then it comes back   The serial port is a USB with a BlueTooth connected   I think this guy was having a very similar problem  but not in C   Freeze on SerialPort Open   DeviceIoControl   GetcommState with usbser sys  As best I can estimate  I have read his entire problem  and the resulting comments  and the answer  but I really can t figure out which one fixed his problem  or if C  is significantly different from what he was experiencing   Thanks for any help for the clueless  This is the actual code where it s happening   public static void Open ActivePortWeWillUse String Drone StringNameFromUser        SerialPort TempSerialPort   new SerialPort Drone StringNameFromUser   int  SerialPortSpeed        ThePorts ActivePort1   TempSerialPort       ThePorts ActivePort1 DataBits   8      ThePorts ActivePort1 Parity   Parity None      ThePorts ActivePort1 StopBits   StopBits One       ThePorts ActivePort1 DataReceived    new SerialDataReceivedEventHandler OurBackGroundSerialPortReceiver        ThePorts ActivePort1 Open         Sometimes  Error hits here

User · Answer

I had this problem as well on two different Windows computers when communicating with a Arduino Leonardo. The reliable solution was:

Find the COM port in device manager and open the device properties.
Open the "Port Settings" tab, and click the advanced button.
There, uncheck the box "Use FIFO buffers (required 16550 compatible UART), and press OK.

Unfortunately, I don't know what this feature does, or how it affects this issue. After several PC restarts and a dozen device connection cycles, this is the only thing that reliably fixed the issue.

User · Answer

Too many big files all in one go  Windows barfs  Essentially the copying took too long because you asked too much of the computer and the file locking was locked too long and set a flag off  the flag is a semaphore error   The computer stuffed itself and choked on it  I saw the RAM memory here get progressively filled with a Cache in RAM  Then when filled the subsystem ground to a halt with a semaphore error   I have a workaround  copy or transfer fewer files not one humongous block  Break it down into sets of blocks and send across the files one at a time  maybe a few at a time  but not never the lot   References   https   appuals com how-to-fix-the-semaphore-timeout-period-has-expired-0x80070079   https   www-01 ibm com support docview wss uid swg21094630

User · Answer

This error could also appear if you are having network latency or internet or local network problems   Bridged connections that have a failing counterpart may be the culprit as well

User · Answer

Okay  I am now connecting without the semaphore timeout problem   If anyone reading ever encounters the same thing  I hope that this procedure works for you  but no promises  hey  it s windows   In my case this was Windows 7  I got a little hint from This page on eHow  not sure if that might help anyone or not   So anyway  this was the simple twenty three step procedure that worked for me   Click on start button Choose Control Panel From Control Panel  choose Device Manger From Device Manager  choose Universal Serial Bus Controllers From Universal Serial Bus Controllers  click the little sideways triangle I cannot predict what you ll see on your computer  but on mine I get a long drop-down list Begin the investigation to figure out which one of these members of this list is the culprit      On each member of the drop-down list  right-click on the name A list will open  choose Properties Guesswork time  using the various tabs near the top of the resulting window which opens  make a guess if this is the USB adapter driver which is choking your stuff with semaphore timeouts  Once you have made the proper guess  then close the USB Root Hub Properties window  but leave the Device Manager window open   Physically disonnect anything and everything from that USB hub  Unplug it  Return your mouse pointer to that USB Root Hub in the list which you identified earlier  Right click again Choose Uninstall Let Windows do its thing Wait a little while Power Down the whole computer if you have the time  some say this is required  I think I got away without it  Plug the USB hub back into a USB connector on the PC If the list in the device manager blinks and does a few flash-bulbs  it s okay  Plug the BlueTooth connector back into the USB hub Let windows do its thing some more Within two minutes  I had a working COM port again  no semaphore timeouts    Hope it works for anyone else who may be having a similar problem

User · Answer

I had a similar problem which I solved by changing the Port Settings in the port driver  located in Ports in device manager  to fit the device I was using    For me it was that wrong Bits per second value was set

[c#] "The semaphore timeout period has expired" error for USB connection

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