• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 3212
  • Last Modified:

serial/COM port pass through on ESXi 4.1

I have a virtual machine that needs to use the COM port that is on the main board of the ESXi host.  Can I do COM/Serial port pass through.  I need to send ASCII characters to the VM via this port.  
0
gopher_49
Asked:
gopher_49
  • 4
  • 3
1 Solution
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, this works very well; we use for debugging serial communications.

 Serial Port
Just make sure that the SERIAL port is enabled in the BIOS of the VM, and set to COM1 or COM2 etc, sometimes, change from auto to ENABLE.
0
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
I have a serial-connected device to a VM. It uses the same setting as you stated (/dev/ttyS0). You can only have one VM using the physical host's serial connection, though. (see: http://kb.vmware.com/kb/1001979) If you have issues Get the hostd logs and see if it shows us anything (see: http://kb.vmware.com/kb/1021800)

Normally the Default Operation for Serial Poirts in the Virtual Machine BIOS are set to AUTO.

AUTO - Bios or OS choose configuration.

 VM Serial Ports
Just remember to enable serial ports in the VM BIOS, and VM OS!
0
 
gopher_49Author Commented:
Okay. I'll convert the physical machine to a VM and give it a shot.  I'll know something tomorrow
0
Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

 
gopher_49Author Commented:
In the BIOS I specified COM 1, however, Windows is showing COM2 and COM3.  I don't see anywhere in the VM settings to force a specified COM port.  I'll change my app to look on COM2, however, I figured it would show up as COM1 since I specified COM1 in the BIOS.
0
 
gopher_49Author Commented:
It works...  I changed my app to use COM2 and it's receiving data.  I guess the Windows mapping doesn't match the COM port noted in the BIOS, however, the physical hardware ID configured in the VM matches the hardward ID of COM1 noted in the BIOS.  I guess when it mapped it to Windows it changed the logical COM port number?!  Either way...  It works...
0
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
There is none, COM ports are allocated by I/O address, like in the good old days of DOS! They are allocated at BIOS level. Windows will then do the plug and play!

It's possible the difference between actual physical IO ports, and Logical Name ports!

COM1 is normally 3F8, COM2 is normally 2F8, but Windows gets COM ports confused, and just adds COM2, COM3 etc

As long as you've got data, being received.
0
 
gopher_49Author Commented:
I noticed in the client it shows /dev/char/serial/uart0 as the selected COM port, however, it also shows /uart1/ but there is only one COM port on this server?!  Maybe there is another and I didn't noticed it.  Anyway, I guess Windows got confused and added COM2... Either way.. It works.

thanks.
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

  • 4
  • 3
Tackle projects and never again get stuck behind a technical roadblock.
Join Now