I have a GPS module connected through serial port(USB->Virtual COM port). A measurement software is using this port, so with other software I can't access to the data. I would like to create two virtual COM port and share this data through that. Is it possible using Python? Is there any opensource example written in Python?
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This might work for a test hw-group.com/products/hw_vsp/index_en.htmlMartin Beckett– Martin Beckett2012-01-30 17:46:29 +00:00Commented Jan 30, 2012 at 17:46
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2 Answers
I don't think you can do that if you cannot modify the sources of the measurement software.
Serial port protocols are written as "point to point" protocols, so there's no general way to multiplex them. You can write a program that shares the access to the GPS module (handling it exclusively and exposing an API to multiple programs), but every program that wanted to use the GPS module should be written to talk to your API and not directly to the serial port - and in this case it can be done only if you can change the measurement software.
Notice that probably it's not impossible to implement your "virtual port" solution, but it would be an ad-hoc hack (it would work just with that specific protocol) and it may be quite complicated: you would need to emulate two GPS modules and multiplex the requests to the real GPS module; depending on how does it work (e.g. if it has a "complicated" persistent state) it may be simple or very complicated. But surely Python wouldn't be enough, to emulate serial ports you have to go in kernel mode.
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Do you need two-way communication, or just reading? You could build or buy hardware to physically split the Rx data line so you could use two COM ports, each of which would read the same data. You could do this with Tx data as well, but you would have to be careful about trashing the data if both ports tried to write at the same time.
