How to cvonfigre RS232 to TTL on ESPeasy?

[aihysp]

Hi i have Rs232 serial port converter(ali 1$)
i whuld like to send RS232 commands from nodeMCU
that has ESPEeasy

can anyone tell me how to connect/config

1. where to connect RX/TX? TX>RX? or TX>TX
2. how i send commands?
3. how i configre this device
4. if anyone can give me some exmaple of a command

i understand this is probly a noob Q, its just to send TTL commands but still i have no Clue
please help

[TD-er]

Make sure the serial port converter outputs only 3.3V.
Usually you connect TX to RX and vice verse.
But if it isn't working, try to switch Rx and Tx in ESPeasy.
What do you want to connect? The NodeMCU alread has an USB to serial adapter included in the board. So you can connect to it via the Arduino IDE, or Serial Monitor in PlatformIO.
List of supported commands in ESPeasy: https://www.letscontrolit.com/wiki/inde ... _Reference

[aihysp]

i am using openhab>node-red

i want to know how to inject by MQTT ON,OFF,Etc
to the prjector i have with RS232
i dont want to use USB.... in the end i want somthing like ESP01 on the projector


so my Q is
what do i need to send in node-red(MQTT)
to make it work?

to what pins?
what kind of commands?

soory i having real trouble getting the hang of this....

[TD-er]

I know @grovkillen had done some experiments connecting ESPeasy to his projector.
So maybe he can shed some light on this.
But I guess you will also encounter some issues with signal levels on the device side.
RS232 signal levels are way higher than 3.3V, so you'll probably need a level converter to make sure you do not destroy your ESP device.

[grovkillen]

Yes I've done some experimenting but have not had the time to get it going. I've used the MAX3232 circuit but have not had success in getting my projector responding to my commands (using there "serialsend" command). I need to test with a logic analyzer to see if the MAX3232 is sending anything to the projector. Will also need to try to use a computer instead of only a ESP just to make sure the projector is understanding the RS232 codes.

[LobsterJack]

i am using openhab>node-red

i want to know how to inject by MQTT ON,OFF,Etc
to the prjector i have with RS232
i dont want to use USB.... in the end i want somthing like ESP01 on the projector


so my Q is
what do i need to send in node-red(MQTT)
to make it work?

to what pins?
what kind of commands?

soory i having real trouble getting the hang of this....

I don't know, man. Drawing up a projector cots more than a market can offer, and the most severe price comes in the form of time consumed by development. Maybe top engineers can assemble the project in a few days, but 70% waste a weak and have a malfunctioning garbage :\ Just check this $100 projector and you'll save your money and time.

[Shardan]

Hello all,

several problems may stumble on eachother here.

@Grovkillen:
MAX3232 is an inverting line driver - I'm not sure if the Tx/Rx from the ESP isn't already inverted.
I'll check today at evenng or next weekend, what the output of an ESP8266 does, I've a digital scope at hand.

@all
Some things must be considered with RS232.
- Voltage level.
RS232 uses a wide voltage range. Originally it was designed for at least +12..15 V for logical "0" and - 12...15 V als logical "I".
As most PC's used just +/- 5 V RS232 should (!) allow +3..15V and -3..15 V.
But mind the "should"... The ESP offers 3V and 0 V so this might not work with any RS232 device.
That's what serial adapters like the MAX3232 is for.

- Logical level
RS232 is an inverted protocoll! Positive voltage says logically "zero", negative voltage says logically "one".
I've to check what the ESP gives on the serial port, it might be alreday inverted or not.
Without sending any data the TX line should have positive voltage!

- "Specials" with ESP8266
Don't forget to disable the serial log. Serial log will confuse the other side waiting for commands instead logs.
Remember, that even with switched-off log the ESP8266 sends some data on boot that may conflict with your device.

[Shardan]

Hello again,

just checked the serial out with my DSO.
It recorded the first few bits of a serial transmission on the ESP's TxD pin.
.

ESP_TxD-Out.jpg (74.74 KiB) Viewed 6031 times

.
Obviously the ESP sends already the correct inverted logic signal.
It his on 3,2V when idle and the first edge of the "Start" bit goes to zero.

So the MAX3232 will invert the already inverted signal again which is not the desired signal.
(And obviously i have to recalibrate my DSO probes..... spikes, spikes, spikes....)