HiLetgo 5pcs RS232 to TTL Converter Module COM Serial Port Board MAX3232 MAX232CSE

I've bought multiple packs of these over the past few years. They all have been consistent with each other, with the expected chips, even years between purchases. I develop software for networking equipment and use them for serial consoles on many various switches, routers, and access points. They're reliable and work well. The people saying the TX/RX labels are reversed are correct. Those saying they aren't don't seem to understand how they're supposed to function. TX/RX on TTL adapters normally refers to the signal direction relative to the adapter. So the normal circumstance is you connect a UART header's TX to the RX of the TTL adapter (UART sends, TTL receives), and the UART header's RX to the TX of the TTL adapter (UART receives, TTL sends). With this adapter, its labels refer to where you plug it in on the UART header. Adapter's RX to UART RX and adapter's TX to UART TX. The only possible downside I see is you can't use only TX, RX and GND with these, unlike most USB to TTL adapters. Voltage is required for the adapter to function, and it has a red LED which illuminates when it receives power. That's fine for my use case, but might not be for others.

So, I used this TTL to connect my scale with a RS232 output. Then connected to Arduino Nano for the logic functions of reading the scale info and then only printing the weight value from the scale in numeric and barcode format. It’s a dedicated solution I was targeting for and succeeded. After finalizing the code and electronic connections I then 3d printed a case to enclose all components. Turned out really nice. The printer uses the hardware serial rx and rx while the scale uses software serial1 for the scale rx and rx.

Used for several rs232 experiments with ttl and serial lines. Worked with 5v high ttl lines but some setups like 5v vcc added with some did not, you need to test which setup works for you. Tested at 300 and 1200 baud, was able to tx over a 15ft cable.

Great product for the money. Mine were all RS3232 chips and output correct voltage. Unfortunately, the pin labled txd is actually rxd and rxd is txd. A lame mistake by the maufacturer but once you know, they work well. Using this for serial testing with a LibreComputer "Le Potato" connected to pins 4,6,8,10 which map to /dev/ttyAML6 once you "ldto enable uarta". I would buy more but this came with 5x units. All set for four more projects.

I saw reviews that said the PCB was marked incorrectly, that the chip was a MAX232 instead of a MAX3232 and the chip overheated. I did not see any of these issues. All 5 of my boards had MAX3232 chips installed, were marked correctly and ran cool. Note that the "schematic" shown (also attached) is completely wrong. GND of the CPU is shown connected to RXD, CPU TXD is connected to GND and CPU RXD is connected to TXD. The correct connection is CPU GND to GND (obviously), CPU TXD to TXD and CPU RXD to RXD. I connected the board to a TI MSP430F5338 and it works fine at 115.2K when connected to my PC. I would have preferred that the 4 pin connector was ship separately as I used wires to connect the board, but I just wired to the back of the board. Not mentioned in the documentation is a red LED power indicator.

I was using this to convert the TTL from the Arduino to the RS232 of my Stone HMI display. Then I got brave and removed the 4 SMT resistors on the Display and re-soldered them on the TTL line. Now I don't need these, but they were very good for testing functionality before doing surface mount soldering...

It worked as documented and desired. What more could I want?

These do NOT work with 3.3V VCC as the MAX3232 spec indicates they should. They only work with 5V VCC. Do not use with Raspberry Pi 3.3V UART, as the 5V VCC results in an overvoltage on the 3.3V UART pins.