I have installed a moxa cp-114EL multiport serial board in a hp server dl380 g9 with vmware esxi 6.5.
I've created a windows server 2012 R2 virtual machine with the card configured in direct I/O (passthroug).
The card is well recognized and installed by the windows server with latest drivers and all the com ports are ok,
but when i open the port com, no data is received.
When trying the card directly in a physical windows 7, the transmission is ok.
Do you have an idea of what can block communication?
esxi log can he give me informations ?
Can windows server security possibly block serial communication?
Thank you very much.
I guess, the device is not certified by VMware and there is the root cause of the issue.
Please check the any device compatibility with ESXi before buy on this portal:
VMware Compatibility Guide - System Search
Considering the VM recognises the serial card maybe something else is wrong.
Is the VM virtual firmware using BIOS or EFI? If it is using BIOS, the default is that COM1: and COM2: are enabled in the virtual BIOS. What are the serial COM assignments for the MOXA ports? Either change the MOXA serial port assignment (maybe change it to COM3:, COM4:, etc) or disable the serial ports in the virtual BIOS (if VM is using BIOS).
You can refer to this KB on how to enter the virtual BIOS. Using the bios.forceSetupOnce = "TRUE" works also for ESXi VMs.
I have pasted two screenshots from the virtual BIOS from Fusion (should be same for ESXi VMs). Go to the Advanced and I/O Device configuration and you can disable the serial A and serial B. In the screenshot of serial A and B, I made it as "Enabled" to be obvious but the default is "Auto". There should be a "Disable" option. I don't think there is any serial setting is the virtual firmware is EFI.
We have the exact same problem. Did you manage to solve it?