Hi All,

I'm having some problems using Boost ASIO on Windows XPSP3, 32 bit.

I'm trying to set-up an asynchronous read from a serial port on the computer (actually a USB port masquerading as a serial port). The code is at

http://gist.github.com/634618

We regularly call the function
PCTimeoutUart::wait( iseSize_t len, uint32 timeoutInMS ) which wraps the calls to the boost asio libraries.

This creates a deadline_timer, and binds it to our timeout callback (PCTimeoutUart::finishedTimer)
It also calls async_read_some on the boost::asio::serial_port object  m_port to read the required length, and binds that to the PCTimeoutUart::finishedRead callback.

We call the runone() function on m_io, which is declared in the header as a boost::asio::io_service and has been passed to both the timer and serial port's constructors.

We continually call this in a loop until either m_timedOut has been set by the asynchronous call back to PCTimeoutUart::finishedTimer
or m_finishedRead has been set via the call back to PCTimeoutUart::finishedRead

Normally, this works well. However, there are certain scenarios when it fails to write anything to the buffer, despite the fact that finishedRead() is called with error = 0 and the correct length . I've checked by initializing the buffers with a couple of different values and each time, it's clear that the buffer is being passed back without those values being altered. Strangely, it is always when the string sent by the external device is '\r\nNACK:XX\r\n'   where XX is a 2 character ascii number.

I've got portmon running on the serial port and it confirms that the data has been correctly received from the external device.

We've debugged it as far as putting a break-point on line 71 and at that point can see that the system thinks that a read is complete, n bytes have been returned, but only some of those bytes are in buffer.
If anyone could offer any views on why we may be having problems, or places that we could look, then that would be very much appreciated.

Thanks in advance,

Jim