NOOB question on VMWare Workstation and Serial Ports

[Tony_Goodhew]

Hi All,

I've just download the trial for VMWare Workstation (it's the current version 12.1.1 build-3770994) as I'm thinking of buying a license to help automate some of the old HP test gear I have here at home (they have automation software that expects to have a MSDOS machine). So far I have MS-DOS 6.22 installed on the VM and everything seems to be working but I'm running into a problem getting the serial port configured to work with the National Instruments GPIB drivers.

Because this is all old gear, I bought a GPIB-232CT-A RS232 to GPIB adapter. I've tested this setup using a really old laptop I have here and it works but when I try to get it working from my main PC under VMWare it seems like the software can't communicate via serial. At the point where the software on the laptop would start talking to the serial device the VM seems to hang/take much longer than expected before it fails out (unfortunately without an errors so no helpful debug info there).

On my main machine here the serial port is actually an additional PCI-Express card and surfaces as COM5 & 6 - This card works as I'm using COM5 to talk via serial to my GPSDO. I've configured the VM to have a serial port and I've tried to follow the suggestions in various posts but it doesn't make any difference. SO I thought I'd ask the community for help.

Here is the relevant part of the VMX file:

serial0.present = "TRUE"

serial0.fileType = "device"

serial0.fileName = "COM6"

serial0.tryNoRxLoss = "FALSE"

serial0.autodetect = "FALSE"

I've attached the VMX to this post - If anyone has any suggestions I'd really appreciate the help as I'd like to get everything running on my main desktop instead of almost 20 year old laptop machines.

The GPIB drivers are the CTDOS27 ones from National Instruments.

Thanks in advance and apologies if this is a trivial question that is well documented somewhere that I couldn't find.

TonyG

[Tony_Goodhew]

Just bringing this back up to the top of the forum as I'm running out of time in my trial and I've still had no luck in getting the serial port to work.

Please let me know if you have any suggestions at all as I think it'd be a great solution for me to get rid of these other old DOS machines.

Thanks,

TonyG

[Scillonian]

‌Does the GPIB-232CT-A RS232 to GPIB adapter use a proprietary signalling scheme at the serial port end?

I've only ever been able to get serial devices that use standard signalling such as printers and modems to work with VMs. Any devices that used proprietary signalling such as an APC UPS I could never get to work. (Admittedly this was in the VMware Workstation 6 era and I haven't used any serial devices since.)

[Tony_Goodhew]

Thanks for the reply, appreciate it.

I don't actually know. I can certainly put my scope on it and decode the interaction but I'm not an RS-232 expert so I probably couldn't tell you by looking at the decode.

What was the APC twiddling? I assume it was raising things like DTR, CTS, DSR, etch out of order compared to a modem.

TonyG

[Scillonian]

From an old pinout diagram I found for the UPS cable at the time the PC connection I think was:

• Pins 1 & 4 (DCD, DTR): Linked/Shorted
• Pin 2 (Rx): AC Fail signal from UPS
• Pin 3 (Tx): UPS Shutdown signal from PC (controlled by UPS software)
• Pin 5 (Gnd): Common
• Pins 7 & 8 (RTS, CTS): Linked/Shorted

These cables also did not work with USB to serial adaptors which again, like the virtual serial ports, emmulate a serial port.

[Tony_Goodhew]

There musty be something going on because I was able to go from Putty on my Windows desktop to Kermit running on the MSDOS VM and pass characters back and forward.

However, I've had no luck trying to get the GPIB software to work correctly (and I haven't thrown my scope across the wires to check either as I'd have to build a custom breakout board - I never did get around to purchasing one of these).

Anyway, if anyone has suggestion s on getting serial to work with more than just modems, I'm all ears.

Thanks,

TonyG

[Tony_Goodhew]

On a lark, I decided to put Windows 3.11 onto a new VM and then use the National Instruments Windows Drivers to see if it works.

Surprise - Yes it does, correctly identifies the serial GPIB controller and passes the out of box tests.

So there must be something unique about the way the DOS app talks to the serial port that doesn't happen when going through the Windows serial drivers.

Now I just need to see if the DOS utilities I needed to use will work under these drivers.

TonyG

[jiml888]

Win 3.11 was a shell on top of DOS.  So I would suspect your utilities WILL work.

[Tony_Goodhew]

Unfortunately there seems to be a difference between how the "Serial Port<->VMWare<->Windows<->Windows GPIB Driver<->GPIB Test Program" and "Serial Port<->VMWare<->MSDOS GPIB Driver<->GPIB Test Program" works.

The actual GPIB drivers are different and they poke the HW differently. Whatever the DOS driver does isn't allowed under Windows (according to other National Instruments documentation).

My summation here is that VMWare will work happily with how Windows talks to the HW (GPIB Driver<->Windows Serial API <-> Serial HW) but doesn't like how the driver was talking to directly to the serial HW.

Thems the breaks I guess - Looks like I'm back to just using the old laptop again and when it finally dies, I'll just get an el'cheapo motherboard with a serial port on it.

Thanks everyone for the help though - Appreciate it.

TonyG

[wila]

Hi,

Haven't played with this in a while and I certainly do not intend to send you on a wild goose chase, but have you looked into the configuration of the serial port that you are trying to use in the VMware virtual BIOS?

Eg. perhaps your MS-DOS configuration is expected different interrupts/IO ports as what it is currently configured for.

--

Wil