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TTL to RS485 Serial Converter Module – First Unit
I picked up this TTL to RS485 Converter Module because I needed a low-cost, hardware-based solution for serial communication between microcontrollers and industrial devices. I was curious to test whether a budget module from AliExpress could really hold up in a more demanding environment like an automation setup using Arduino and Modbus protocols.
Shipping was surprisingly fast — about two and a half weeks to my door in the Midwest. The packaging was basic (bubble wrap inside a small padded envelope), but all the pins were intact and none of the modules had visible defects or soldering issues.
This first unit I tested worked right out of the gate. The automatic flow control feature (no need to manually toggle RTS) made wiring incredibly simple. I powered it using a 3.3V supply on a NodeMCU, and it ran clean data with zero glitches during multiple read/write tests over 48 hours. Heat generation was minimal, and signal integrity over 20 meters of CAT6 was solid — no dropouts.
Pros:
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Works with both 3.3V and 5V logic
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Auto direction control removes code-side complexity
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Stable communication even at 9600 and 115200 baud rates
Cons:
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No LED indicators for TX/RX or power
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Screw terminals would have made quick testing easier
In the US, a similar RS485 module from Adafruit or SparkFun costs $6–9 per piece. On AliExpress, I got 10 units for about the price of one domestic board. It felt almost too good to be true — but this one definitely met expectations.
$3.62
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TTL to RS485 Serial Converter Module – Second Unit
For this second board, I used it in a Raspberry Pi setup for home energy monitoring. I wanted to isolate the UART connection and feed data to a Modbus-compatible energy meter. What drew me in again was the compatibility with multiple voltage levels and no need for software-managed flow control.
Delivery was as reliable as the first one. I tried this board with a 5V logic line straight from the Pi’s GPIO, and it didn’t overheat or cause any bus errors, even with some slight electrical noise in the system. The IC used seems to have decent noise immunity, which I didn’t expect at this price point.
Pros:
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True plug-and-play functionality
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Affordable price point for large-scale IoT deployments
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Minimal power draw
Cons:
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No mounting holes
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Not labeled very clearly (beginners might get confused with pinout)
Compared to US equivalents, I saved roughly 85%, and honestly, I wouldn’t have been able to outfit all my DIY nodes with US-sourced boards without blowing my hobby budget.
$2.33
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TTL to RS485 Serial Converter Module – Third Unit
I grabbed this third board to test in a classroom environment for a small workshop I was teaching on industrial communication protocols. This module’s simplicity is what attracted me — no special drivers, just solid UART to RS485 conversion.
I soldered header pins to this one and let students experiment with it. Despite being manhandled and miswired once or twice, it survived. That durability was a pleasant surprise. Communication was stable across a lab bench setup with a PLC simulating slave devices.
Pros:
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Strong enough to tolerate minor abuse
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Versatile for teaching, prototyping, or field use
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Surprisingly good signal isolation
Cons:
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Requires soldering if you want to use jumper wires
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Would love to see a conformal coating for harsh environments
It performed well enough that I plan to use more of these in future workshops. For $0.60–$0.80 each, they absolutely beat the $7–$10 SparkFun options.
$3.62
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TTL to RS485 Serial Converter Module – Fourth Unit
This fourth module was used to convert UART from a Wemos D1 Mini to RS485 to drive a stepper motor controller. I needed precision timing and didn’t want to mess with software-managed transmission direction.
Again, it worked straight out of the package. I appreciate how consistent these modules have been. There’s a kind of minimalist charm to them — no frills, just does the job.
Pros:
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Consistent build quality
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No need to tweak software for TX/RX switching
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Easy to daisy chain for multi-node setups
Cons:
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Would benefit from reverse polarity protection
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SMD components are unbranded (so long-term reliability is a question)
Against US products at 10x the price, these continue to impress. I’m honestly stunned they perform as well as they do under real-world loads.
$2.33
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TTL to RS485 Serial Converter Module – Fifth Unit
I used this fifth unit in a remote irrigation control system that communicates with soil sensors via Modbus RTU. These modules are perfect for field use where long distances and voltage interference could be an issue.
I tested it over a 100-foot run of shielded cable and didn’t lose a single packet. That shocked me. Most modules in this price range would choke or misfire. These didn’t. At all.
Pros:
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Rock-solid communication even over long distances
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Minimal EMI issues
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Compatible with both STM32 and ESP8266 setups
Cons:
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Not ESD-protected
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Needs better documentation
There’s no way I could source something like this locally for under $1. These units paid for themselves almost instantly.
$3.62
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TTL to RS485 Serial Converter Module – Sixth Unit
This unit went into a solar battery monitor project. It was powered by a 5V regulator from a lithium pack and ran for 3 days continuously with no hiccups.
What impressed me here was low idle draw — important in solar scenarios — and reliable auto direction handling even when power conditions weren’t ideal.
Pros:
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Very energy efficient
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Simple 4-wire hookup
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Clear silkscreen markings (on this batch, at least)
Cons:
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Exposed PCB edges
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No onboard protection circuitry
In the US, I’d have spent $8 for a lower-efficiency module. These definitely surpassed what I expected from budget RS485 hardware.
$2.33
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TTL to RS485 Serial Converter Module – Seventh Unit
I plugged this into a BeagleBone Black board running Debian for testing Modbus slave response under real-time constraints. No errors were logged during stress testing. I even pushed it to 115200 baud for fun and it kept up.
Pros:
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Reliable at high speeds
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Compatible with various dev boards
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Handles continuous polling very well
Cons:
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Thin PCB feels a bit flimsy
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Ground loop protection would be a bonus
Absolutely exceeded what I’d expect from a <$1 board. Definitely production-worthy for budget-conscious builds.
$3.62
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TTL to RS485 Serial Converter Module – Eighth Unit
Used in an HVAC system test rig. Needed robust comms between a temperature controller and display. It did great over unshielded wire in a metal environment.
Pros:
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Good noise rejection
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Compatible with legacy systems
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Tiny footprint
Cons:
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No connector pins included
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Poorly printed markings on some
I’m shocked this performs as well as a $12 RS485 dongle I bought locally last year.
$2.33
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TTL to RS485 Serial Converter Module – Ninth Unit
Used with a custom STM32 dev board for robotic arm telemetry. The module helped with clear signal over 6 feet of cable among motors and sensors. Flawless.
Pros:
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Works with STM and ESP boards
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Excellent for noisy signal environments
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Low latency
Cons:
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No built-in termination resistors
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Mounting solution needed DIY effort
Can’t believe I’ve been paying US prices for boards half this good.
$3.62
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TTL to RS485 Serial Converter Module – Tenth Unit
Deployed this one in a test network with four nodes. The module had no issues with multiple transmitters. Great for my initial RS485 multi-drop experiments.
Pros:
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Supports daisy-chaining well
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Easy to integrate into test setups
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Durable enough for repeated insertions
Cons:
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Sharp solder points on the back
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Could use a simple test button
Just as solid as premium models from US suppliers. Buying these in bulk was a smart move.
$2.33
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TTL to RS485 Serial Converter Module – Eleventh Unit
Tried this unit with an ESP32-S3 to test OTA RS485 bootloading. The signal never broke, even during firmware uploads. That’s rare at this price point.
Pros:
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Great for dev use
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Surprisingly tolerant of power noise
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Stable under continuous load
Cons:
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Minimal component labeling
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No pin headers provided
Really impressed. I honestly thought I’d hit a few duds by now — but no.
$3.62
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TTL to RS485 Serial Converter Module – Twelfth Unit
Final test: connected it to a micro PLC (Siemens LOGO! clone) to exchange sensor data. Communication was seamless. The PLC didn’t even flinch during high traffic.
Pros:
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Excellent compatibility with PLCs
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Simple wiring
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High reliability
Cons:
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Needs hot glue to secure in some enclosures
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Slightly fragile pads when re-soldering
Even after 12 tests, I can’t find a bad one in the batch. That says a lot.
$2.33
Overall Opinion
I’m genuinely surprised by how consistent and functional all 12 of these TTL to RS485 converter modules turned out to be. For a budget product, I expected at least a couple of failures or annoyances — but every unit worked straight out of the package and integrated smoothly into different hardware environments. These modules offer incredible value, especially for DIY electronics, prototyping, and even some light industrial applications. Compared to overpriced US-based options, this is a no-brainer. I absolutely plan to order more and would recommend them to anyone building out RS485 networks on a budget.
