Does VarAC allow multiple instances to access a single GPS device?

Hi,

Is VarAC designed to let multiple instances share a single GPS device?

What I observe: When I run two instances of VarAC with GPS enabled, each one competes for the GPS port. They take turns every ~30 seconds, so only one has GPS data at a time. I expected the first instance would grab the port and keep it, without letting the other use it.

What I’d like to know:

Is VarAC designed to let multiple instances share GPS access?
Or should GPS be enabled on only one instance, with its data automatically shared to other running instances?

Environment:

OS: Linux (running VARA and VarAC under WINE)
VarAC: 12.0.0
GPS: USB receiver on /dev/ttyACM0 mapped to COM5 in WINE

VarAC.log:

19/09/2025 23:30:29 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:31:00 - (CN:2) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:31:33 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:32:10 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:32:41 - (CN:1) Error: Unable to read GPS data. Attempt 2/5. Retry in 30 seconds.

19/09/2025 23:33:19 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:33:50 - (CN:2) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:34:24 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:34:58 - (CN:1) Error: Unable to read GPS data. Attempt 2/5. Retry in 30 seconds.

19/09/2025 23:35:31 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:36:04 - (CN:1) Error: Unable to read GPS data. Attempt 2/5. Retry in 30 seconds.

19/09/2025 23:36:36 - (CN:2) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

19/09/2025 23:37:07 - (CN:1) Error: Unable to read GPS data. Attempt 1/5. Retry in 30 seconds.

Thanks as always,

Gene / JI1BQW

Comments (5)

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Gene Ishikawa

Sep 28

Thanks, Irad and Gary. That clears it up. I’ll look forward to seeing this improvement in the future, but no rush.

irad d

Sep 27

Hi Gene

Com ports in PCs can be used by a single entity only. So only one instance can have access to it.

I still dont have a mechanism to share GPS data among cluster but that it a good idea that I will add to the todo list.

In the meantime - what Gary suggest is a great solution which I use by the way for other purposes - when I want multiple software work directly with a RIG comport

73s

Irad

NC3Z Gary

Sep 21

In use 1 GPS device to feed 5 instances of VarAC, I simply use a GPS Splitter software called VSPE. And thanks for providing screenshots, it does help tremendously.

My bad. Forgot to attach screenshots. Here you are.