Slow execution of CLOSE instruction

[myk]

Just run into an odd problem.


I need to generate a "break" sequence over the COM port (a long low going pulse).
I am using the long recognised method of changing to a slow baud rate and printing an ascii zero.


Works fine, but in order to run at the lower baud rate I end up with sequential CLOSE, OPEN, CLOSE operations, and the CLOSE operation seems to take a length of time related to the last-set baud rate.


CLOSE at 75 baud takes almost 2 seconds

.
.

Has anyone else observed this effect
Is there any way to work around it ??

[Rod]

Well I have not tried this myself but the serial port should respond to escapeCommFunction() commands but you will need Liberty BASIC because they are API based.

This LBPE article discusses escapecommfunction in its later chapters. It shows DTR and RTS handling but should also respond to _SETBREAK and _CLRBREAK If Liberty does not know these constants use 8 and 9 respectively in place of the constant.

Let us know how you get on.


alycesrestaurant.com/lbpe/AccessingSerialPort.html


docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-escapecommfunction

[myk]

Thanks for that !
If I upgrade to Liberty basic I will give that a go

For now however I am using JustBasic (I probably should have made that clear) so I suspect I am stuck with the effect