Shopping Cart

Your cart is empty.

Your cart is empty.

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

4.5 (10) Write Review
Free shipping on orders over $29.99

$19.90

$ 7 .99 $7.99

In Stock

1.Style:Db9 Mf


About this item

  • Connect in series with any RS-232 interface for testing a serial RS-232 data link. Simple and easy, no oscilloscope is needed. DIP switch can setting disconnect or reconnect any signal, and support external probe test signal from male or female position.
  • 8 double-color (red and green) LEDs indicate the logic states for respective data lines. Green for logic HIGH and red for logic LOW. Full RS232 spec compliant with LEDs for all 8 signals: DCD, RXD, TXD, DTR, DSR, RTS, CTS, RI.
  • No external power required. No driver required. Plug and play. Jack sockets(nuts) on the tester can be unscrewed easily(with metal shell held in place) if needed to mate with another connector that has jack sockets.
  • OS Compatibility: Windows 98, Me, XP, 2000, 2003, CE, Vista, Windows 7, and Windows 8 as well as Linux and Mac OS 10.X, ect.


Product Description

RS232 Breakout Tester LED Monitor, DB9 Male to Female Breakout Module. CZH-LABS OONO F-1023

  • Connect in series with any RS-232 interface for testing a serial RS-232 data link. Simple and easy, no oscilloscope is needed. DIP switch can setting disconnect or reconnect any signal, and support external probe test signal from male or female position.
  • 8 double-color (red and green) LEDs indicate the logic states for respective data lines. Green for logic HIGH and red for logic LOW. Full RS232 spec compliant with LEDs for all 8 signals: DCD, RXD, TXD, DTR, DSR, RTS, CTS, RI.
  • No external power required. No driver required. Plug and play. Jack sockets(nuts) on the tester can be unscrewed easily(with metal shell held in place) if needed to mate with another connector that has jack sockets.
  • OS Compatibility: Windows 98, Me, XP, 2000, 2003, CE, Vista, Windows 7, and Windows 8 as well as Linux and Mac OS 10.X, ect.
  • Typical application scenarios: Watching the TXD and RXD LEDs either changing states or flashing to know data transferring direction: from machine to computer or from computer to machine. Verifying TXD/RXD wires should be wired crossed(swap pin2 and 3) or straight through by observing TXD and RXD LEDs at a rest state. Verifying it is a DTE or DCE device (and whether you need a null modem or not). Verifying whether modem controls are active, even if they're not being asserted. Testing control signal between control systems (AMX, Crestron, etc) and the devices they control. Determining if the serial connection is mated properly and if communications is occurring. Whether the wall control or the projector is malfunctioning.
F-1023 1
F-1023 7
F-1023 8

Marc Niegowski
2025-08-09 18:07:42
It works very well. Use 22AWG solid wire. 24AWG works as well, but I find it a little sloppy. 22AWG fits perfectly and snug. Some people complain about the upside down DB9s - I say: “So what?”. It’s a great little tool. The photo shows a typical null modem configuration.
Kauai Jim
2025-06-29 13:21:55
Great price. Fast shipping. Worked great.
Dave
2025-05-06 11:03:09
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.
Brent
2025-03-09 16:49:45
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.)
azog
2025-03-05 17:35:19
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.
Josh
2025-01-20 17:19:16
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.
Ogi
2024-12-28 12:16:32
Good for RS232 monitoring and troubleshooting.
Dan
2024-12-23 18:57:09
The rows of pin sockets on the front of the device are too small diameter to accept a standard component or jumper pin.
jgohn
2024-12-03 15:53:07
Perfect
く
2024-11-15 13:52:37
ジャンパワイヤが刺さりそうな穴が開いていますが、デュポンコネクタのオスより一回り細く、刺さりません。できれば、刺さるようにしておいて欲しかったです。