Bluetooth Serial Adapter

I found this on Amazon. DSD TECH SH-B23A Bluetooth 2.0 to RS232 Serial Adapter with DB9 Converter. The pictures in the Amazon listing didn’t show jumpers. Some sites say you need to hold the switch while powering up others just change the jumpers ahead of time. I think it depends on what hardware DSDTECH actually ships you.

Software to set the baud rate can be downloaded from DSDTech-Global

Manual for the device.

Set the baud rate. For me I connected a serial adapter to the serial port on SH-B23A and set BAUD to 9600 and com port to 7 and selected the tab for HC-05 in the software. Set the jumpers to Device and powered up the SH-B23A then pushed the micro-button and the DSDTECH tool software would get an ok when I sent an AT command. There is going to be some trial and error here as it seems like they ship different hardware depending on what is available. Mine shipped with the jumpers on PC and it wouldn’t do anything until I switched them to device. I drilled a hole in the case so I could reach that little switch with a paper clip, but it seems like I won’t need to move the jumpers just leave them on Device.

I missed on the first attempt and had to drill a second hole.

Other reviews and users had this work. Disassemble unit, then ensure 2 jumpers are on “PC” pins to set correct baud rate, then use command tab HC-05 in software (not SH-B23 which is what this device is supposed to be!), open UART, select correct Comm port on your computer, press micro-button inside device, then press “test” in software and most importantly, receive an “ok”.

Button if needed

Remember to switch the jumpers from “PC” back to “device” after changing baud rate.


If you don’t get an “OK” after pressing “test”, you’re not connected to your computer. And even though it looks like you are changing the device parameters in the software, you are not. Worse, You will still be able to “connect” or “pair” via blue tooth with another device, but the baud rate likely won’t be correct (because you never actually changed it) and it will be connected via blue-tooth, but it won’t work (ie will not transmit data).

I used Windows 10 for my setup, may not matter.

Comm ports used for me are 11 and 12, it seems random which one communication will happen on. Most times it worked on comm 11 but after a few reboots it worked on comm 12.

Connected to the USB port on the front of a switch it is a little flaky.

I am going to cut some holes in the case so I can press the micro button and move the jumpers without taking out the screws. Just need to use tweezers and something like a paper clip to push that button.

Instructable with setup information. Another version with slightly different setup steps.

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