how to get serial port in Windows VM working in ESXI

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epicurean

Active Member
Sep 29, 2014
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Been trying to get a physical serial port on the esxi 5.5 host to work in a windows VM without any success.

Tried in both windows 7 and Windows 10 and windows 2008 server.

Anyone has any ideas?
 

c912039

New Member
Apr 25, 2012
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Whilst I am not able to make any suggestions regarding getting the physical serial port on your ESX host passed through, I can comment on the solution I ended up with.
I needed to virtualize a physical host that had lots of serial and serial type USB devices connected. The ESX host was quite some distance from where the serial and usb devices were terminated.

So I used a combination of Digi International's AnywhereUSB device (USB over IP) and their Edgeport Serial to USB converters. I located those devices at the USB and serial cable termination points, and loaded up the drivers in the Windows VM.
Apart from having to delay startup of the processes that communicate over those serial and USB devices in the virtualized Windows client, the solution has been rock solid.
 
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epicurean

Active Member
Sep 29, 2014
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thanks for the suggestion. But I am trying to find a cheaper solution , as opposed to buying more hardware to support the serial port.
 

NetWise

Active Member
Jun 29, 2012
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Edmonton, AB, Canada
What exactly is the issue your running up against? I do this fairly regularly and it's dead simple. Add the serial port to the VM, power it on, fire up putty, connect to whatever is on the physical port.

Are you getting some manner of error message?
 

epicurean

Active Member
Sep 29, 2014
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I need a serial null modem cable to be connected to a serial port , for management control of my infiniband switch.
unfortunately, this sun x2821a switch uses a usb port which needs a usb to serial adapter. I can do so easily with any stand alone windows PC , and putty in.

When I try to give a serial port (using the physical port from the esxi host) to any windows VM, even though everything is detected , putty in and there is no response from the switch. I can only assume I am doing something wrong. I also configure the bios of the VM to have only 1 serial port, still no response.
 

NetWise

Active Member
Jun 29, 2012
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Edmonton, AB, Canada
Try connecting to another device and confirm its not that switch or the USB/serial requirement. There's nothing un-obvious about how to do it as you've indicated so it should 'just work'?
 

epicurean

Active Member
Sep 29, 2014
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Try connecting to another device and confirm its not that switch or the USB/serial requirement. There's nothing un-obvious about how to do it as you've indicated so it should 'just work'?
I have no issues with the first serial port on the host, which i gave to VMA primarily to control the APC ups. Dunno why the 2ne serial port would not work with any windows VM I tried
 

NetWise

Active Member
Jun 29, 2012
596
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Edmonton, AB, Canada
I've never done more than one per host. I don't think that serial redirection has any basis on PCI passthru. But I do know when you're trying to pas through things like quad port NIC's there is often two NIC's per chip, and they have to go together. I'm wondering if you assign both serial ports to the same VM what happens? Maybe it's just that they cannot be split up.
 

epicurean

Active Member
Sep 29, 2014
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Hi Netwise,
You got a point there. It never occured to me that the 2 serial ports cannot be split up.
 

DorianJ

New Member
Sep 26, 2017
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Have you tried to forward a serial port to Windows VM via the network using the software solutions? Serial over ethernet will do that job just fine, and no additional hardware is required in that case