[Tutor] Fwd: Re: Lost message re serial comms

[Alan Gauld]

On 01/02/15 14:28, Alan Gauld wrote:

> So, in Python I found pyserial and wish to use it to send binary to
> controlled devices (in this case to a Modbus protocol solar charge
> controller (TriStar TS-60).
>
> In C++ I would setup ‘structs’ or class attributes to hold the byte
> oriented commands and controller responses and then send them to rs232
> as binary.  I do not see how to do that with pyserial.

Its not a PySerial function but Python allows you to define classes 
which can hold yoiuur data for you just like C++ Any reasonable python 
tutorial will tell you about the syntax.

Alternatively you could use the more advanced data types in Python to do 
the same thing, either a dictionary or even a list or tuple could be used.

> What I need is to send and receive binary (not strings) over rs232.

The struct module is possibly what you need.
It contains functions somewhat like sprintf() and sscanf() in C.
You can convert binary data into byte strings and vice versa.

> this case from/to a Raspberry Pi (RPI) controller to/from the solar
> charge controller.  The RPI runs apache server to handle the network.

The type of computer is probably irrelevant for this case, although the 
OS and python version are not. Lets assume Linux and Python 2.7

Pyserial and struct and a dictionary or class should do all you need.

-- 
Alan G
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