RS232 Breakout Tester LED Monitor, DB9 Male to Female Breakout Module

I needed a way to verify that the signal from the software was getting from the computer to the end of the cable. This did exactly that for me!

My application wasn't very sophisticated, but this did show me what was going on with the serial connection I was troubleshooting.

What it does:1. Show while lines are disconnected, low, and highno light = disconnectedred = lowgreen = high2. Allow any lines to be turned off (DIP switches)3. Allow jumpers (to cross-over, for example)Issues:1. Jumper cables don't fit (the holes are too small)2. Resistors barely fit (but at least they're quite snug once pushed into place)3. It's upside down!Why would the lights be placed on the wrong side? Most equipment I've encountered has the larger portion on top (like my 2nd image), so the display is facing away from you.This is not an RS-232 analyzer. It just shows the individual lines and allows you to turn individual ones off for debugging, or to cross them using very thin wire, such as a low-value resistor, which I had handy. (This allows you to create a crossover connection like a null modem cable for debugging your connection.)(In the photo, I've turned off all, but the TX, RX, and Gnd connections for testing a microcontroller connection.)

This breakout tester is absolutely essential for anyone working with serial communication on a regular basis.The problem with serial communication is that it either works or it doesn't, and there is very little, if any, sign of that's wrong, and there could be any number of things wrong.I cannot count how many times I've wired up a connection between two devices and had it not work. Did I use a null modem cable? Or is the device wired so I should be using a straight through cable? Is the device sending data? Maybe the baud rate is set wrong. Is the COM port I'm plugged into the right one? Or worse... what if two or more of those things are wrong?I guess I'll have to haul out other cables, a logic probe and a power source to run it, maybe a meter, and some little tiny wires to stick into those DB9 connectors to probe the pinout... Gimme an hour and maybe I'll have it working, you say to yourself....This one little simple gadget solves all of that. Do I need a null modem cable or a straight through, or is the cable really what I think it is? Flip two switches and place a couple jumpers to reverse the TX and RX lines, and find out, without hunting around for other cables or busting out a meter to figure out what kind of cable you have.Want to know if the host is sending data? Is the peripheral responding? Are the send and receive happening on the right lines? No problem, look at the LEDs on the front and I know, at a glance.If your communication is more complex and is using the other pins, there are LEDs to tell you those statuses too.Want to snoop the line? No problem, just grab an FTDI cable and some jumpers and you can spy on the communication using the jumper ports. Or, use a second one of these boxes and do the same.I cannot state enough how much time this saves and how useful it is. It's small enough to carry around in a toolbox, robust enough to get banged up a good bit over time, and requires no batteries or additional power sources, it's powered by the line itself.I only wish I had bought one of these years ago.

Compact and easy to use. Seems like it’s good quality too!

This thing is like the Swiss Army knife when you need to troubleshoot RS232 / serial communications. It can connect almost any possible combination of 25 or 9 pin cables, and can connect most signal to any other signal. The only thing I find kinda annoying is that all the connectors have standoffs, which doesn't work well when your existing cable already has standoffs! But not annoying enough to ding the usefulness of this thing.

This device works great for observing and debugging RS-232 stuff. Some folks complain about the test points not accepting dupont cables, they're sized for resistor leads, some breadboard cables (with round pins) and non-stacking arduino headers will also plug into them for use with dupont connector if needed (non stacking means the standard headers you'd find on arduino UNO, not the ones with long pins used on shields). They used the round socket strips because they had the same height as the dip switches. Photo shows RS-232 reconfigured with 10ohm resistors as an Agilent crossover cable, which solved the problem I got it to solve. The case was too bulky to plug directly into the back of my Agilent 34401A, so I used a stack of gender changers to get clearance.

Are the days of serial data interception over? Maybe not. My plan is to insert this between an older piece of gear that sports a DB9 serial port and a USB to serial port adaptor in order to reverse engineer a data stream to a vector graphics robotic renderer. We'll see if my plan will work or not. Even if it does not, I am old school enough to appreciate having one of these in my tools/widgets piece-parts.