Xojo Serial port stopped

In Windows 10 I’m communicating with an AMS SIN-11 USB that interfaces with an AMS stepper driver using a CP210x USB to UART Bridge Virtual COM Port (VCP) driver. All was working yesterday, but when I started today, with no code changes, my Xojo code is not sending or receiving anything over the serial port. But all still works fine on the same port in Hyperterminal. The port opens fine in Xojo, but nothing is sent or received. The physical connection is Comm3 and Xojo opens Comm3 even when it is already open in Hyperterminal. But whether or not Hyperterminal has the port open, Xojo does not send or receive anything.
How could serial communication differ between Hyperterminal and Xojo? Both are communicating at 9600 baud, 8 bit, no parity, 1 stop bit and no handshaking.

Have you re-started the PC (completely)? The following statement suggests to me that Xojo is not really opening the port: “The physical connection is Comm3 and Xojo opens Comm3 even when it is already open in Hyperterminal.”. If you have a port open in Windows by one application and try to open it in another application, Windows will send you a nasty message box (best case), the application will hang (bad case), or the application will act as if the port opened and communication was established (worst case) but nothing will happen. I would suspect that something happened between yesterday and today that has messed up the communication between Xojo and the Com port. And when everything else fails in Windows, you re-start everything.

Thanks Langue, I had rebooted the computer before I wrote previously, and did it again just now. My code was the first thing to run, and still the same problem, serial1.open returns True, but no communication either way. But all worked fine when I then opened Hyperterminal on the same port.

And now I’m seeing the same problem on a Mac, but communication works find when subsequently using a program called Serial.

I’m going to take a break. A two day old version of my code works, and I can’t see where it differs with the code that doesn’t work, but that must be where the problem is.

Did you remove a serial.reset by accident or is it happening out of sequence?

Can you save the two code bases in text or vcp format so you can compare them? Maybe you inadvertently changed a setting on the serial component. But given that you think you opened the port while using it in hyperterm leads me to believe that you are not really opening the port (again, perhaps some unknown change in the code).