Gather data from a PLC to a Raspberry Pi running Debian and then broadcast it on internet

Question

I have an Unitronics V570 PLC which takes temperature readings. An Ethernet card enabled PLC is really expensive so I plan to connect the PLC to a Raspeberry PI. How can I use Python functions that allow the computer to connect to web pages. I will eventually build a web site with PHP that will accept a connection from the Raspberry Pi. I will then let the web page load the data into a MySQL database and operators can view this data online.

My question is: How can I connect the raspberry Pi to the PLC to extract all the data I would need to send to the web page. The Rpi has a serial port built into its GPIO connector and I have built an interface that would allow serial connection between the Rpi and the PLC. How can I establish connections between the Rpi and the PLC? I will be using RS232 communications from the PLC to Rpi

Answer 1

For RS232 your looking for power, Txd and Rxd (pin 8 and 10)

http://elinux.org/RPi_Low-level_peripherals#General_Purpose_Input.2FOutput_.28GPIO.29

These are all included in the GPIO

you can use this python side to read and write

http://pyserial.sourceforge.net/

You may need to adjust the power lines

once the data is in python you can save it or re send it to another database.