Raspberry to (usb) RS485

[Emdek]

Hi,

I've been searching for a while now, can't figure it out myself:

I want to control screens and shutters from a webinterface by sending hexadecimal commands over serial. It has to be RS485, that's the only interface the controlling device has on board.

My idea was to use a Raspberry Pi in combination with a USB to RS485 serial adapter (PL-2303). This works, I installed Raspbian Wheezy and I can succesfully control the interface using python scripts from a terminal screen. 

The next step was to run the python scripts from a web interface. I installed Apache, PHP etc but can't find a simple way to run my python scripts from the webinterface.

I stumbled upon WebIOPi, which seems to be just what I need: a simple webserver to control other devices with serial commands. I can't figure out though how I can send an hex string to the USB0 serial device.

One of the strings I need to send (and which works running a python script from terminal) is \x7F\xF2\xFA\x01\x00\x00\xAE\x78\xFA\xFF\xFB\x06\x86

Should I focus on running my (working) python script using WebIOpi or shoud I use a different approach?
Please advise.

Emdek

[Emdek]

Forgot something: I can configure WebIOPi to use usb0 in the conf file, but I can only set the speed/baudrate, not parity etc. Any ideas?

Op zaterdag 25 januari 2014 17:31:53 UTC+1 schreef Emdek:

[Maciek Wąchalski]

You should start with Serial Tutorial:

https://code.google.com/p/webiopi/wiki/Tutorial_Serial

[Eric PTAK]

advanced serial settings like parity is not provided. common UART settings is used (8N1 ? I don't remember)

don't know if you need different settings for RS485 ?

you don't need apache/php, WebIOPi is all-in-one including http server.

You have to begins with the basic tutorial, you will understand how webiopi works.

https://code.google.com/p/webiopi/wiki/Tutorial_Basis

Then go further with macros, then serial.

In order to send bytes, you need to use writeBytes function from a python script, and avoid using the REST API as mentioned in the tutorial.

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[Charudatt Uplap]

Hi Emdek, did you get what you are looking for ? I have a similar requirement to turn ON/OFF relay board over RS485.

http://circuitsonweb.blogspot.in/2013/02/8-relay-control-board-over-rs485.html

Thank you.