This is the newest revision and fixes issues with the last board. This breakout board pairs an SP3485 RS-485 transceiver with an FT232RL USB UART IC to convert a USB stream to RS-485. The SP3485 is a half-duplex transceiver, so it can only communicate one way at a time, but it can reach transmission speeds of up to 10Mbps.
The TXDEN pin of the FT232RL is connected to the transmit and receive enable inputs of the SP3485, this line is used to control the transmission mode of the RS-485 transceiver. With the proper drivers installed, the FT232RL will enumerate as a virtual COM port; the drivers are available for Windows, Mac and Linux.
This breakout board includes the SP3485, FT232, TX/RX/RTS LEDs, Mini-B USB connector, filter capacitors, and other components shown on the schematic. We’ve broken out the RS485 output to three different connections: (1) an RJ-45 connector, (2) a 3-pin 3.55mm screw terminal, and (3) a 3-pin 0.1" pitch header; none of these output connectors come populated.
Measuring with the caliper, here are some dimensions:
width = ~23.57mm (one side of PCB to the other side of the PCB)
length = ~40.40mm (end of the PCB to the edge of the mini-B connector)
height = 1.65mm (measured from the bottom of the PCB to the top of the PCB)
maximum height = (~5.71mm from the bottom of the PCB to the top of the mini-B connector)
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Based on 6 ratings:
Simple. Straightforward. Just hook it up per the pinout and go. Add a RJ45 and make it easier.
The description states “Driver/Receiver Enable connected to RTS line of FT232RL” but the schematic shows that the driver receiver/receiver enable is connected to TXDEN. Which is it?
I bought 10 Pc. Three of the units work ok. Seven of them do not work.
I have checked the converters with an oscilloscope and a multimeter. In the bad pieces, level of Rx pin of the SP3485 is low, and when data arrives goes to high without following the incoming data. Resistance between Vcc and Rx pins is infinite. In the good pieces, level of Rx pin is high, and when data arrives follows data correctly. Resistance between Vcc and Rx pins is high, but not infinite.
I wait for your comments Regards Daniel
Hmm, this is not an issue we’ve seen before. I’ll do some testing on some boards, and contact you directly to resolve this for you.
Bought this to interface an RS-485 sonar I purchased. Loved the price and size, but I had intermittent communications issues. Neither Sparkfun nor the sonar company could help me get it to work. Ended up buying a more expensive converter from another company which worked perfectly.
It has been working for over 3 months, no issues. I’m using it to communicate a Raspberry with a driver of a huge motor that powers a fan.
The schematic says TX is red and Rx is green but on my board the silkscreen TX and RX marks seem to be on the wrong LEDs. When the board transmits the red LED with silkscreen label RX lights up, while when the board receives, the green LED labelled TX lights up.
Apart from that the board is great.
The LEDs follow traffic on the RS-485 side of the board rather than the traffic on the USB side so they will appear backwards from what you’re expecting.