Recently, I was working on a Test Automation project where a few AC to DC Converter Boards need to be tested automatically using a fully automatic test zig.
In order to connect various board used in the test automation solution I decided to use RS485/Modbus as communication interface. For the same I ordered Waveshare’s USB to RS485 RS232 TTL Converter which is USB powered and isolated converter. Isolation is very important when you are working on a solution which will be used in Industrial environment.
As soon as I received it, I was curious to know how they have designed the board, what all components they have used. how they achieved the isolation. So, I decided to open it and see what is inside 🙂
I am sharing the picture below so that you can see and learn what is there inside this USB to RS485 RS232 TTL converter.
I found the quality good and it worked well without any issues.
They have used USB type B connector as USB interface, which is a good choice as USB-B is much more rugged than Micro USB connectors.
Then they have used FTDI Chip (FT232RL) for USB to UART conversion.
LEDs for USB Power, RX and TX activity is provided.
A clear isolation is done using MORSUN DC-DC Converter module (B0505LS-1W) for power and Analog Devices ADUM1411 for digital signals. You will also be able to see the PCB slot cut is provided to improve the creapage.
On the output side, you get three sections:
TTL section on removable screw terminal, gives access to UART TTL level signals (RX, TX, GND), you can select if signals need to be 3.3V or 5V level using slider switch.
RS485 section has A+, B- and GND on the removable screw terminal gives access to RS485 interface. For RS485 they have used transceiver IC SIPEX SP485EE which converts UART signals to RS485 signals and then via protection circuit it connects to the screw terminal.
Good that they have provided removable screw terminal, this helps when you want to remove the converter to isolate the converter to troubleshoot in case any thing gets damaged.
On RS232 side they have used SIPEX SP3232EEN for UART to RS232 signal level conversion. They have provided DB9 male connector for RS232 interface.
I hope you found this post useful. If you have any feedback, you can share in the comments section or you can also directly contact me.
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Great article, thanks.
Question about RS232, what is the pinout of DB9 connector? Does it have all signals or only Tx/Rx/GND?