September 16th, 2008 
Kiwi Si 
I have just gone to add a serial connection from my APC UPS to my management server which is running under on a VM on ESXi.
I powered down the VM and then went to add a serial port.
Only to be presented with the ‘Use physical serial port on the host’ Serial Port Output option greyed out.
This is also true when trying to add a pass-through parallel port.
After a quick bit of hunting around it would appear that the serial and parallel port pass-through functionality is not yet enabled in VMware ESXi. It’s not a licensing issue either as my instance of ESXi is licensed.
I know that this is probably a case of RTFM but I thought this worth a quick blog post as others are bound to fall into this same trap.
Technorati Tags: VMware,ESXi,Serial,Parallal,port,grey,grayed,Serial Port Output,Use physical serial port on the host
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Posted in 
My name is Simon Seagrave and I am a London (UK) based Senior Technology Consultant and vSpecialist working for EMC. 
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Simon,
I know you mentioned its probably an RTFM thing, but I’ve been looking over them for about an hour this morning. Been trying to find the same answer you came up with. Thanks for the easy (ier) to find info on your blog!
[Reply]
bitterbuds Reply:
July 27th, 2010 at 1:00 am
Hi
At the end VMWare has the solution. Upgrade to ESXi 4.1 will solve this issue.
http://www.vmware.com/products/vsphere-hypervisor/
Cheers
Bitterbuds
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jerome Reply:
August 11th, 2010 at 8:45 am
Installed 4.1 and was able to connect the physical serial to the vmware.
sadly the parallel one is still not able to work
[Reply]
Kiwi Si Reply:
August 11th, 2010 at 9:46 am
Hi Jerome,
Thanks for taking the time to let us know. I have yet to try this though hope to get some time soon.
Cheers,
Si
It’s been this way in 3i for a while.
http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1003129&sliceId=2&docTypeID=DT_KB_1_1&dialogID=558195&stateId=0%200%20556582
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This can’t be fuck true? No support for physical serial port? What a fuck – back to the stone age. Thank god we have Microsoft virtual server and XEN. This is major major bug!
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Thanks for the Post saved me a lot of time.
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Not sure that I agree that it is a bug.. I think I understand the design. The idea is that VM’s need to be disassociated from their hardware to allow for fluid movement of VM’s from machine to machine. By adding the dependency upon a serial/parallel port, especially on a server, you add a likely failure in the process of migrating a VM from one ESX server to another.
The solution that seems the most feasible is to get a serial-over-ip adapter such as the Digi One SP (http://www.digi.com/products/serialservers/digionesp.jsp).
Personally, I’ve never had consistent luck with ESX and pass through to the serial port, especially with Windows VM’s.
[Reply]
Kiwi Si Reply:
May 15th, 2009 at 10:58 pm
Hi Rich,
Totally agree – definitely not a bug but a necessity for when using features such as HA, DRS and now FT in vSphere.
I haven’t used any of the serial/parallel over IP adapters before and have mixed reports on how good they re. If you end up trying one such as the Digi One SP you mentioned let me know how you get on – it’d be interested to know how you find it.
Thanks for taking the time to leave a comment.
Cheers,
Si
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Hi saw this as I was searching for answers on how to connect my APC UPS via serial or USB to my ESXi host.
I’m using ESXi 4 and the option is greyed out. Also I can see in the log that when I connect my APC UPS via USB it is detected by the host, but I can’t pass it through to a VM.
Any solution apart from buying an expensive APC Network Management Card?
Thanks
[Reply]
Kiwi Si Reply:
August 7th, 2009 at 6:22 pm
Hi Cookie,
I haven’t heard of a way before unfortunately. If you had a management card you could use the method outlined here (http://viops.vmware.com/home/docs/DOC-1341) to shut down your ESX server.
Let me know if you ever find a way of doing this.
All the best,
Si
[Reply]
I think what ESX/ESXi/vSphere is missing is the ability of monitoring UPS! So far all the ‘method’ I found are hacked together with apcupsd and vMA. Can’t VMware have native UPS support like what Windows has?
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I have seen several posts that calim a Serial-ovr-IP device can get around the problem that you cannot tie a VM to the Physical Serial Port on the physical ESXi3.5 Host. But not once has anyone ever explained exactly how you would approch doing that. Please don’t assume all of us readers are just going to already know where to begin with doing that. I use many serial-over-IP devices on our LAN,…oe more is no big deal,…but I don’t know how to approach it with ESXi3.5 and the VM that needs to receive data over a serial port.
Are there any documents explaing the approach? I have no problem with RTFM if I know what I am supposed to read and where I can find it. Now before someone dumps some 300 page Manual on me and says “read it”,…at least tell me where in those 300 pages to look,…I’m growing older by the second,…life is short.
Thanks in advanced guys!
Phil
[Reply]
Kiwi Si Reply:
January 16th, 2010 at 3:30 pm
Hi Phil,
To be honest I have had very little to do with serial over IP devices before so can’t really comment. I would like to get my hands on one so at least I could give it a try and kick the tyres on it.
If anyone else has any experience on this topic or knows of any decent documents out there that may assist then please let Phil and myself know – thanks.
Phil: Sorry this isn’t more of an informative answer.
Cheers,
Simon
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I did some more digging and found someone who said that there was a unitlity that would be indstalled on the VM PC that would emulate the Com Port ansd tie it to the IP# of the Serial-over-IP device. So I checked the disk that came with mine and sure enough there was such a utuility. I tried it and it worked more or less,..but in my situation i have the serial line split with a splitter because I have two machine reading the same data. There is already one serial over IP device involved and when I added the second to the mix there was soem kind of conflict that the data would stop flowing. So I had to abandon the VM idea and go back to a physical machine in this situation. But in a more normal situation it probably would have worked fine.
I was using Moxa NPort 311′s (www.moxa.com)
Maybe this will help someone.
Phil
[Reply]
Simon Thomson Reply:
February 25th, 2010 at 2:01 am
Just a little FYI on the serial over IP device we are using. It is a Belkin F5L009 and is working in our environment to connect our APC UPS to a VM under ESX 4i.
The device requires a sofware agent in the VM, Windows only. It works best in XP and Server 2K3 32 bit. Can be made to work in Server 2K8 and x64 but you need to be a little creative.
You need to have a USB device added to your VM (I finally found a use for that option) and you cannot start your UPS control service automatically as the USB connection is now provided in software post boot. I have found a startup script that sleeps for 30 secs and then starts the apcupsd service works well. A method to power the thing from the UPS is also required (hint: it can be powered via USB)
I know that the Digi devices are on the VMware HCL but those things are $500 and we are a very small business, the Belkin device goes for $100.
The setup works and apcupsd recieves the signals it needs to but it is definitley a ‘hacked’ solution. Here’s hoping that VMware and the UPS vendors can come up with better solutions for this gaping hole in virtualisation infrastructure soon.
Simon.T.
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Hi Guys,
I’m with all you on this one. I just got my client to dig out his UPS serial cable and connect it between his APC 1500 VA UPS and the serial port on his IBM Rackmount VM host on ESXi 4, assuming I would be able to map it through somehow, but no joy. Hopefully VMware might do something about this soon. Our virtual host is a single vm host in the network. We use the virtualisation just for better utilisation of the high-end server hardware, and improved remote support. We aren’t using any vmotion or anything like that, so a direct connected serial port is not a problem, and the ability to monitor the UPS and allow for graceful shutdown of the fileserver through the directly connected serial cable would be very helpful.
This is definitely an area where VMware needs to come to the party and enable the feature.
Chris.
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did a second test this morning with esxi 4.1 on different hardware for parallele port, still no luck.
on the bright side, serial port via usb seems to work aswell(the 2nd pc dell optiplex 960 had par but no serial)
Sadly we have to give up the idea of having a vmware with dos 6.2 as we need both serial/par for specialised instrument.
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I perform an upgrade of ESXi 4.0 host to ESXi 4.1, and the option “Use physical serial port on the host” is unavailable (Greyed Out).
Any idea?
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