ESP8266 Community Forum

- Thu Apr 07, 2016 7:13 am #45033

Is there some ready-made board say with a DB9 or direct pin connections?

BTW, it is even worst : real RS232 signal is swinging between around -7V and +7V, inverted compared to TTL side, -7V is HIGH and +7V is LOW.

You need to use some interface chip such as MAX232, which built the +-7V out from 5V using internal charge pumps.

YES. Check ebay for rs232 to TTL converters/adapters.

Gary

- Thu Apr 07, 2016 9:59 am #45049 Thanks, will try to source required part.

Is there some ready-made board say with a DB9 or direct pin connections?

BTW, it is even worst : real RS232 signal is swinging between around -7V and +7V, inverted compared to TTL side, -7V is HIGH and +7V is LOW.

You need to use some interface chip such as MAX232, which built the +-7V out from 5V using internal charge pumps.

YES. Check ebay for rs232 to TTL converters/adapters.

- Thu Apr 07, 2016 6:44 pm #45078 The serial interface module you have found looks ideal for interfacing to your solar inverter.
Now, the NodeMCUv1.0 board has a serial to USB chip on it. I would recommend that you continue to use that for its intended use i.e. uploading code and as a debugging port.
Use Softserial to create another separate serial port (with dedicated tx and rx pins) to communicate with the solar inverter. This way you will have the debugging capability needed for parsing the incoming data and tracking what is happening with ThingSpeak communications etc.

- Thu Apr 07, 2016 7:47 pm #45079

The serial interface module you have found looks ideal for interfacing to your solar inverter.
Now, the NodeMCUv1.0 board has a serial to USB chip on it. I would recommend that you continue to use that for its intended use i.e. uploading code and as a debugging port.
Use Softserial to create another separate serial port (with dedicated tx and rx pins) to communicate with the solar inverter. This way you will have the debugging capability needed for parsing the incoming data and tracking what is happening with ThingSpeak communications etc.

Here is a ebay rs232 to ttl converter..
http://www.ebay.com/itm/2pcs-MAX3232-RS ... SwLVZVg6IW
You will need to step the 5v down to 3v but that can be done with couple of resistors and voltage divider

Gary