[ModEdit, related ticket #17116: Serial device data not transmitted to Win XP guest]
VirtualBox V5.1.14
Host: Win 7 Ultimate
Guest: Win XP Pro
We attach a power supply unit (PSU) to serial port COM1 of the physical machine running Win 7.
The PSU sends status data to COM1 permanently.
In the guest (WinXP) the virtual serial port COM1 is mapped to the real serial port COM1.
This is the serial port configuration in the guest:
- "Enable Serial Port": Checked
"Port Number": COM1 IRQ: 4 I/O Port: 0x3F8
"Port Mode": Host Device
"Connect to existing pipe/socket": Checked
"Path/Address": COM1
Now the Problem:
When we start the VM the application doesn't receive the status data initially.
Only if we send any character from the VM to COM1, the status data is received by the monitor application as expected.
Further we can see, if we don't send a character to COM1, close the VM and start it again, the PSU status data is received at once.
This succeeds as long as we don't reboot the host.
After rebooting the host the next time and starting the VM receiving the PSU status data fails again.
It seems, that VirtualBox requires sending some data to the serial port first, before it is able to receive data from the serial port.
By the way, running the monitoring application in the host works perfectly.
What do we do wrong ? Any help will be appreciated.