HiLetgo 5pcs TTL to RS485 485 to Serial UART Level Reciprocal Hardware Automatic Flow Control UART to RS485 Converter RS485 to TTL

First, I purchased this because it has Automatic Flow Control! WHAT A DREAM! Saves a lot in programming. Although, the programming for this using Arduino Nano's (V3 and ESP32 S3) is a breeze! Awesome board, easy set up and works fantastically. The price, being second, I dont know if you can find Automatic flow control with any boards as inexpensive as this! I use many of them for communication between all my Arduino's and 5 at a time is great!

I'm using these to experiment with rs485 connections between raspberry Pi boards and Pi Pico boards. There are some limitations to be aware of, i.e. these are half duplex and don't have control signal lines so communicating both ways can get complex. These work at 3.3V so you can hook them up directly to the gpio pins. I don't know how much 3.3V will limit the range but I've been doing tests on about 15 meter cables.

I used this between a PZEM-017 and an ESP32 to monitor DC current/voltage. Worked as expected, but note that alot of the online references show TX to RX and RX to TX. I found that this RS485 adapter worked only with TX to TX and RX to RX. outside of that worked perfectly. I only wish it had external led pins for TX/RX led connections.

These RS485 modules are a major improvement over older models that require manual flow control. The automatic flow control works flawlessly, making them much easier to integrate into a project. As other reviewers have noted, wiring is straightforward: TX on your Arduino (or similar device) connects to TX on the module, and RX to RX. For the RS485 side, B- connects to B-, and A+ to A+. On the receiving unit, TX and RX follow the same mapping. I used the spare pair in an RJ11 twisted pair cable to carry VCC and GND between the modules, which worked perfectly. In the demo video, you can see a yellow LED flashing once per second—this is triggered across the RS485 link. There's also a built-in LED on the ItsyBitsy board flashing every five seconds, controlling a relay at the other end. The TX/RX LEDs on both modules flicker as data is sent and received, confirming everything is working as expected. I’m giving 4 stars instead of 5 because the physical design is awkward for use with solderless breadboards. The modules are so long that you need to place two standard breadboards side by side just to accommodate them once the headers are soldered. A shorter, more compact form factor would have been much more convenient.

Doing its job.

Over 5 months of use (ESP32 with a Growatt solar Inverter) I've gone through all 5. After a month or so, these burn out. LEDs flicker or fail to light, and there is no data getting through. Swapping in a new one restores functionality. I'm done with these and trying an "industrial" version (like the Waveshare DIN mounted or similar) next.

I do a lot of Home Assistant builds and have used many different types of device. These RS485 controllers have auto flow control and are by far the easiest to get working, especially for novices to this protocol.

Have other issues in the circuit but by the tx/rx lights a 3.3 on one side and 5 on the other seems to work just fine. Soldered the termination resistor enables, they somewhat share a ground, and the reference is simply connected through one half of a pair in the ethernet I used.