You want to monitor values of a PLC, controller, OPC, HMI or SCADA that is Master Modbus RTU and write in spreadsheets from Google (Google Docs), In this case we will monitor the value of potentiometer V0 PLC from 0 to 100%:
Potentiometer V0 (0-1000 SCALE 0 -100%)
ESP8266 Connection Script and Google – Google Spreadsheets
-01 ESP8266 connecting with Google Script and connection with the spreadsheet from Google (Google Docs) Direct.
Based on the library HTTPS Redirect for ESP8266 of electronicsguy Github I have set and have made several improvements, I created the following tutorial full to Connect ESP8266 with (Google Script) and (Google Spreadsheets)
Connection ESP8266 and Panasonic PLC via Modbus RTU (RS232)
Modbus RTU Slave ESP8266 -01 PLC Panasonic FPX C14R Master Modbus RTU (RS232).
Video Complete Test
In a nutshell
ESP8266 monitors the values in Registers Holding PLC and insert them into the spreadsheet.
MAX232 (RS232) + MAX485 (RS485) + ESP8266 – 01
Data insertion time
Every 15 seconds minimum, to avoid saturating the ESP8266.
Materials Very cheaps!!
1 PLC FPX C14R Panasonic
1 Cassette COM4 RS232
1 ESP8266-01 Aliexpress
1 Regulator 5v a 3.3v
1 Power supply 5v
Downloads – Complete Project