The Null Modem test was conducted with this configuration
UARTCFG COM1 19200 8O1
ECHO "Hello World" > COM1:
The other test computer had the same Baud Rate setting (COM1 19200 801).
I have proven that your software (UARTCFG ) works correctly with the 19200 8O1 on the VirtualBox UART setup.
How certain are you that the communications preferences at what you say thay are for the device, i.e. 19200 8O1? I already pointed out that this is an unusual configuration (as in, I've been using serial ports for 40 years and never heard of anyone using that config: most software wouldn't even offer the possibility). Can you change the configuration of the device to 8N1 or 7E1?
I am 100% certain that is the communication preference (19200 8O1). I have used this configuration on the old DELL Laptop and I can get it to communicate with the real hardware.
Please note the external hardware is a custom communication box that was built 20-30 years ago. The firmware/boot code/communication was probably all custom for this hardware. I have no way of changing the internal firmware or software inside the device.
I have a full functional Old Dell Laptop that uses a built-in serial COM Port to communicate with the external device. I used your UARTCFG tool to set the baud rate and preferences on the old Dell Laptop and I was able to establish communicate with the device no problem. When I try to do the same thing on the Virtual Box and the external device, then it fails.
Side Note....
I have tried other experiments with other products to solve this issue as well and I have had limited success.
DOSBOX Test - I used a DOSBOX emulator with a 19200 and communication preferences and I have been able to establish communication with the external device. I had to set the CPU emulation to be slow (pentium II) to be able to establish communication. The problem is that DOSBOX is only about 10-20% reliable on establishing communication and running the batch file script.
VMWare Test - I can set Baud Rate 19200 and Communication Preference, but no control over the CPU Speed. I have never been able to establish communication with the hardware device.
VirtualBox Test - I can set Baud Rate 19200 and Communication Preference, but no control over CPU Speed. I have never been able to establish communication with the hardware device.
Old DELL Laptop Hardware - I can set the Baud Rate 19200 and Communication Preference (CPU Speed -300 MHz) and I can communicate with the real hardware device. 100% reliable.
This problem has been baffling my mind for few weeks now. How is it possible that a 15-20 years old laptop ($50) is more reliable than all the virtual environments on modern computers? I would like to believe that this problem can be resolved on a virtual setup. I am not sure what I could be missing to resolve this problem.
Any suggestions/comments/feedback are welcome.
Thanks in advance