Am Donnerstag, 5. September 2013, 17:51:18 schrieb Dmitry Timoshkov: > Wolfgang Walter <w...@stwm.de> wrote: > > > > When we send 17 bytes with 150 baud, no parity, one stop bit then > > > > we need to wait at least 17*10/150 seconds > 1000 ms > > > > > > Under Windows with both real COM-port and USB-serial cable this test > > > takes > > > no longer than 890 ms, usually it's even shorter like 875 ms. Testbot > > > VMs > > > also don't fail this test. If under Wine it takes > 1000 ms for you then > > > probably there is a bug somewhere. > > > > How can that be? If you send 17 bytes which expands to 170 raw bits and > > you > > only sent 150 bits/s? > > > > Maybe you are using a virtual machine or your com port does not support > > 150 > > baud and chooses a different speed. Or you use a UART with a large buffer > > and which already signals TX-EMPTY even if it is still sending from an > > internal buffer. But one should not rely on that. > > I'm testing under 64-bit Windows 7 on real hardware.
Then it is your UART or it's driver. As I sad: you need 1133 ms to transmit 17 bytes and I think one should not wait less. Otherwise one depends on hardware, driver internals (linux as windows) and scheduling. One should even wait longer (that is the reason I add TIMEOUT). Regards, -- Wolfgang Walter Studentenwerk München Anstalt des öffentlichen Rechts Abteilungsleiter IT Leopoldstraße 15 80802 München
