Re: [Emc-users] Modbus

[Claude F. <me...@bl...>]

another possibility with python:

https://code.google.com/p/modbus-tk/ (work with serial and ethernet 
modbus protocol, very handy)

for serial, the adaptor I use mostly  : 
http://sigma-shop.com/product/68/usb-to-rs485-ftdi-interface-board-pcb.html 
    work with my specific hardware @500kbauds, up to 10 devices on the 
bus, without troubles.

I have done already some hal module that make remote action from Gcode 
command, I may look back for an example if you want.

for serial communication, a good trick is to add a weak polarisation of 
the bus, like this http://saphum.com/content/rs485-line-polarization (I 
use 390 ohms), soldered on the back of adaptor.

I end up making my how board for USB/RS485, that include these resistor 
(no galvanic insulation yet, as I don't have trouble, this may comes 
latter!)

Claude

Le 18.12.2014 17:13, Carsten Presser a écrit :
> I am using this python lib:
> https://pypi.python.org/pypi/MinimalModbus/0.6
> together with this adapter:
> www.ebay.de/itm/111326580742
>
> Its not FTDI, but the drivers are also in the linux-kernel. No need to
> compile or patch anything.
>
> The Software is just a few lines in python to interface it with HAL.
>
>
>
> Am 18.12.2014 um 12:53 schrieb 77dab:
>> Hi all,
>> I have on my hand some mitsubishi VFD with 550w winches.
>> I would like to try to move them using LinuxCNC.
>> the thing is not meant to be Real time, and I've read the modbus module
>> lives in User space and it's not RT.
>> So, my question:
>> Since it isn't RT, can I drive the rs485 thru a USB->rs485 converter,
>> using a laptop?
>>
>> Thanks, Davide.
>>