Hi, I'm using a gsm modem for sending sms messages, the modem is rs232 so I have to use and ftdi adapter. You can use these with pyserial in a thread in twisted. It uses AT commands, I have one from sierra wireless, some phones can do the same. 3G/internet is something else, here you just need something the operating system will support, twisted doesn't care how you are connected. Bram op 22-09-14 16:01, Simon Andrieu schreef:

Hi,

I work for a company that develops telemetry boxes, and that uses the Twisted framework running on the main board.

It is planned to integrate a cellular module connected via USB or serial link to the main board.

Could you help me to know if GPRS/3G/Modem protocols through USB are supported with Twisted please? And how it is possible to use this interface?

Thanks for your help.

Best Regards,

Simon Andrieu

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No specific reason actually, I didn't even know twisted had support for a serial port. This being said: ftdio_sio can be a bit buggy at times, esp when using multiple devices on the same pc, ftdi on freebsd & osx isn't very stable either. I use this interface selector system where the serial connection can be setup with pyserial,libftdi (which works much better for ftdi adapters) or a tcp socket (which uses a so called "device server" with ethernet and rs232 onboard). Doing it with twisted seems more complicated to me (but I could be wrong), in my case it makes a lot of sense to wait for the data, I poll plc's over rs485 and those kind of things. Also as I've said, there are sometimes a lot of hardware issues (usb bus resets and stuff, users that disconnect usb-ports and plug them back in) which can be difficult to deal with. How long does twisted has this serial port support actually ? Bram op 22-09-14 17:05, Laurens Van Houtven schreef:

Hi Bram & Simon,

I'll answer both e-mails in one go :-)

On 22 Sep 2014, at 16:57, Bram Van Steenlandt wrote:

...

I'm using a gsm modem for sending sms messages, the modem is rs232 so I have to use and ftdi adapter. You can use these with pyserial in a thread in twisted. Huh! Interesting; what drove that choice, given twisted's serial support?

...

op 22-09-14 16:01, Simon Andrieu schreef:

...

Could you help me to know if GPRS/3G/Modem protocols through USB are supported with Twisted please? And how it is possible to use this interface? Depends what that thing exposes. Usually it's a character device, so you end up whistling some bytes. However, if you are *just* interested in a very standard Internet connection setup, it is probably much easier to use the existing OS tools for connecting to the internet using that model, than to write something using Twisted. Twisted would be interesting if you want to do interesting things beyond that; e.g. talk to the device and ask it for all sorts of e.g. telemetry data, data that is not already exposed in some standard, easy to consume way.

hth lvh

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On 22 Sep 2014, at 17:31, Bram Van Steenlandt wrote:

...

No specific reason actually, I didn't even know twisted had support for a serial port.

This being said: ftdio_sio can be a bit buggy at times, esp when using multiple devices on the same pc, ftdi on freebsd & osx isn't very stable either. I use this interface selector system where the serial connection can be setup with pyserial,libftdi (which works much better for ftdi adapters) or a tcp socket (which uses a so called "device server" with ethernet and rs232 onboard). Doing it with twisted seems more complicated to me (but I could be wrong), in my case it makes a lot of sense to wait for the data, I poll plc's over rs485 and those kind of things. Use cases vary :-) In a wait-dosomething-wait scenario, I find @inlineCallbacks to typically yield virtually the same code you ended up with.

When I was doing this, there was some pretty complex chatter back and forth, and I was multiplexing several connections over a single RS232 device, so Twisted certainly came in handy. In your case: don't fix what ain't broken, of course :) Wouldn't it be difficult to combine the twisted method with external

op 22-09-14 18:03, Laurens Van Houtven schreef: libaries like MinimalModbus, libftdi , libartnet etc ? Or is there some magic that I'm not aware of ? I there a disadvantage to using a thread ?

...

Also as I've said, there are sometimes a lot of hardware issues (usb bus resets and stuff, users that disconnect usb-ports and plug them back in) which can be difficult to deal with.

How long does twisted has this serial port support actually ? Well over a decade: Mon Dec 16 04:04:25 2002 to be precise. See svn rev trunk@4528.

hth lvh

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