Strange behaviour while serial printing

Strange behavior when I send a print job to a ticket printer via a serial port.
I open a port via sOpen(Port_E, 5000,5000), after which I send data via swrite(). Then I close the port again with sClose(Port_E)

After the program starts, a dialog box will appear once.
Then it works flawlessly until the program is restarted.
Now there is one customer for whom that dialogue box keeps coming back half the time. That customer must click on the cancel button every 2 tickets.

Does anyone have any idea what's going on here?

Thank you very much in advance.
Willy Hermans

this windows normally opens when you use some printing functions (iprint*)

You can cancel it using iWindowCancel(False) [doc.windev.com]

Regards

Paulo Oliveira

Thanks
It works now.

I've placed it at the start of the project