Ableconn PI232DB9M Compact GPIO TX/RX to DB9M RS232 Serial Expansion Board for Raspberry Pi

I ordered the mSATA version and it is exactly as i expected. The size is about the same footprint as the Pi3 model A+. There is an online wiki but there aren’t that many functions here and it’s pretty easy to figure out. I have partitioned the drive and am running 5 operating systems on the drive for various purposes. It is very slim (height-wise), but i think i can do better: I am going to unsolder the USB pins (which are very nice to have) and put in some right-angled pins to save on space. I also plan on removing the external power port to replace it with something a little different.I can address some issues other people had though:“Blocks the GPIO pins”: this board can be mounted under the pi so that the GPIO pins are still accessible. Pretty easy fix, and you can use shorter headers than provided to keep the whole setup very small. Or get one of those right-angle headers if you still want to mount on top.“USB can’t power the board”: I have tested this with both Pi3 B+ and A+ and this is untrue. I think the problem is with other people’s power supplies. Don’t use a USB charger: amps can fluctuate causing problems with the PI. Instead get a good Power Supply (like Pwr Replacement Chargers) that keeps a constant voltage/amps. I have not had to use the extra power port on the mSATA board because with 3-3.5amps (likely excessive) going into the PI, there is easily enough to run this board with the Pi USB providing both data and power.

I have a DEC vt420 terminal that I had hooked up to a raspberry pi via a USB serial cable. I could never get it to work faster than 9600 baud. In fact, often when there was a lot of text, I would get garbled characters.I had a hunch that the usb serial device was not doing flow control properly, so I bought this board. It took about 15 minutes to install, including the time to solder the pin headers to the pi.It worked perfectly. This serial board is now talking to my terminal at its fastest speed 38400, and no errors.I could not be happier. If you want serial board for your raspberry pi, this is the one for you.

I wanted to use MotionEye as a central NVR for security cameras, and needed fast storage for multiple RTSP and MJPEG video streams to write to simultaneously (SD cards won't cut it).This was pretty simple to configure, thanks to other reviews which deciphered the limited documentation. I've bought other AbleConn (or "A Conn Ble" as their logo implies), so I can vouch that documentation is one way they keep their costs (and prices) pretty dang low.The biggest issue is that there is no case that supports this board, at least not on Amazon. At least none that I could find. I was able mount this onto a GeekWorm RPi 4 case. around (https://www.amazon.com/gp/product/B07X5Y81C6).I don't particularly like having the mSATA board exposed, as this is a "production" system now rather than something to tinker with. If you have some competency with a 3D printer, you might be able to make a nifty case that works with the height of this board. But it seems to work well enough and I can simply lay it on top of my FreeNAS box in the closet to keep it out of the way.If you need mSATA for your RPi and don't mind an exposed board, this is an easy way to go.

This was easy to install and set up. Currently connecting a Crucial 2TB SSD drive. Because of the drive size, I'm powering the board from an external source, not through the Pi USB.So far, everything is working great.

This has a lovely A+ form factor that is sadly crippled by the cable needed to connect the board.The cable adds nearly 3" to the space needed for an A+ (and 2" for a Pi3B).The board could (and should) have been designed to use a flat USB connector bridge.

Device is pretty slow for USB 2.0. It will not get the advertised "480 Mbps". I get 35 MB/s where I should be getting 55-60MB/s. I'm considering returning this as I can get something MUCH faster for the same price.Testing results. All test were from from the same Raspberry Pi 4b.Writing a 1GB file returns 35.5 MB/s----------------------------------------------------------------------------# sync; dd if=/dev/zero of=tempfile bs=1M count=1024; sync1024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 30.2697 s, 35.5 MB/sReading that file from the buffer is 727 MB/s----------------------------------------------------------------------------# dd if=tempfile of=/dev/null bs=1M count=10241024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.47717 s, 727 MB/sFlushing the buffer then doing a read again is 34.2 MB/s----------------------------------------------------------------------------# sudo /sbin/sysctl -w vm.drop_caches=3# dd if=tempfile of=/dev/null bs=1M count=10241024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 31.3989 s, 34.2 MB/sI hook my m.2 SATA drive to my portable enclosure (search for B0892BK5L6) and these are my results. This proves the speed is not the fault of the m.2 SATA drive I'm using.Write----------------------------------------------------------------------------sync; dd if=/dev/zero of=tempfile bs=1M count=1024; sync1024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 3.86467 s, 278 MB/sRead from buffer----------------------------------------------------------------------------# dd if=tempfile of=/dev/null bs=1M count=10241024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.48953 s, 721 MB/sFlush buffer then READ again----------------------------------------------------------------------------# sudo /sbin/sysctl -w vm.drop_caches=3# dd if=tempfile of=/dev/null bs=1M count=10241024+0 records in1024+0 records out1073741824 bytes (1.1 GB, 1.0 GiB) copied, 3.69636 s, 290 MB/s