SainSmart 16-Channel 9-36V USB Relay Module

I’ve only run some test on it because the project it goes in is still a work in progress. But it works fine. I downloaded the software and seems pretty straight forward. Looks like it’s going to be just what I needed.

Baud rate is 9600, no driver required for linux. The hex commands that worked for me are found athttps://s3.us-east-1.amazonaws.com/s3.image.smart/download/101-70-208/101-70-208.zipinside that zip file from the manufacturer is a pdf, 16CH_USB_Relay_Instruction-EN.pdf that has all the commands. Formatted terribly so I can't just simply paste it here.

No documentation came with this, but I managed to find enough information to get it to work on the SainSmart website. I wanted to use it to control some penumatic valves. I noticed that occasionally one of my commands would be ignored, and after some testing I found that there seems to be a flaw in its firmware that will cause it to miss commands if you give the commands too fast. This device is very slow anyway, it only seems to work at a baudrate of 9600 which is much slower than other USB relays. This would have been fine for my application as I only need to switch the valves every few minutes, but the problem is I need to issue a command to close one and open another back to back, and the only way I could get it to perform reliably was to put a rather long delay after every command, which made this useless for my application. I ended up using two separate 8 channel USB relays by a completely different manufacturer.

I purchased two of these cards. Overall this relay is marginal at best and probably not worth the trouble for most people.Overall good:- Low price- 16 channels 1 board- No 'daughter board' for the USB host moduleOverall bad:- No HID compatible software support, no provided drivers for linux, very little documentation- The status command doesn't return anything, which I think would be a key software feature is to check what we think the relay is doing with what the board says the relay is doing.- One of the board makes a whining noise when contact is closed- Tough one for me: there is no hardware level serial number, which means we can't really guarantee we can keep multiple boards addressed properly. There are potentially ways around them, but none of them come without cost and complexity.- No 'plug style' 12v power in like the Knacro 8-channel relay I found on amazon that worked nicely. You have to put in a spliced power chord into screw terminals.The board itself seems sturdy but there seems to be a persistent whine while in the 'on' state once I got them working (after multiple hours of nonsense trying to figure out how to get moving).It isn't supported by most of the major type of relay drivers (such as usbrelay on linux or ondrej1024's excellent relay driver application on github), or even compatible with the other HID type 16 channel relays that Sainsmart also sells. It isn't obvious on the website, but I was finally able to get this to work using a python script I found on github using the serial commands from the Sainsmart Wiki page. Amazon doesn't allow us to post external links in their policy, which is quite frustrating since they profit from this type of poor product with poor documentation. Anyway if you search for RJ QinHeng Electronics HL-340 on gitgist, you can see some code that might help if you use python and pyusb, or mine that I posted (username ldnelso2 on github).My first clue was the device type not being the same as the other sainsmart boards:Device Type:QinHeng Electronics HL-340 USB-Serial adapterThen I found the serial commands to send by copying and pasting from the serial communication document I found here (which isn't obvious from the sainsmart website). Again, Amazon's policy won't allow me to post the link so you will have to search for it by the SKU and find it.You have to add '0x' for hex command sending in the script since you are sending hex over USB , thus in the python script you can define them:# Sainsmart 16-channel commands to modify RJ's python script from the above gitgist link:op_all = [0x3A, 0x46, 0x45, 0x30, 0x46, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x31, 0x30, 0x30, 0x32, 0x30, 0x30, 0x30, 0x30, 0x45, 0x31, 0x0D, 0x0A]cl_all = [0x3A, 0x46, 0x45, 0x30, 0x46, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x31, 0x30, 0x30, 0x32, 0x46, 0x46, 0x46, 0x46, 0x45, 0x33, 0x0D, 0x0A]c6_on=[0x3A, 0x46, 0x45, 0x30, 0x35, 0x30, 0x30, 0x30, 0x35, 0x46, 0x46, 0x30, 0x30, 0x46, 0x39, 0x0D, 0x0A]# and so on. . .Like the other reviewer mentioned, it might be easier to convert the serial commands to decimal from hex and send those, depending on what you are trying to do.So, basically, this card is not worth all the hassle! Go ahead and spend the extra $20 or so and buy a Denkovi USB board. Much better, and way better software, support, and documentation.

The input capacitor should have been a 220uF 50V capacitor. It needed to withstand voltages greater than the 36V the board is rated for. It was a 470uf 16V capacitor. When the board was stuffed, they swapped the two electrolytic capacitors. C9 was installed in place of C10 and vice versa. C9 blew up in less than one minute with 24VDC applied to the input. The switch mode buck regulator failed because of the wrong output filter capacitor. I purchased one board for work and one for personal use, I will repair the one that has not yet been powered on and return the damaged one for an exchange. I will fix it when I receive it. When I first powered it up, I noticed too much input current, so I backed the voltage down to 10VDC. I like how it works, and the Python example provided on the website works perfectly. Also, do not try to power the board from a PC USB port. Remove the jumper P19 and use an external supply to avoid possible damage to your PC USB port. It works well if built properly, this is the reason for the 3 stars.

To control this in python, convert their spreadsheet values from hex to decimal. Excel and office libre has a built in function hex2dec. Put the corresponding row of decimal values separated by commas into a bytearray, then send to serial. Upgraded to 5 star. Been using this thing for a few years to control a semi automatic homebrew system. Once I figured out how to code for it, it was super simple to use. I like that I can control it over usb, was the big selling point. Got it connected to a raspberry pi on a touch screen.

Used a lot of Sainsmart relay products, this one works and will work for most people, but one warning if your using it for a high speed switching environment it is very slow compared to the old HID controller board version. The protocol could be much better for latency, but it is what it is. If you just need to turn a bunch of stuff on and off then this is great. if your switching stuff and expect 100ms or less latency then this is not your product.

good