# TCP receive data led indicator - flip/flop?

**URL:** <https://discourse.nodered.org/t/tcp-receive-data-led-indicator-flip-flop/15506>\
**Category:** General\
**Created:** [13 September 2019 13:18 UTC](https://discourse.nodered.org/t/tcp-receive-data-led-indicator-flip-flop/15506 "2019-09-13T13:18:56Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![thebaldgeek](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/thebaldgeek/32/93523_2.png) [@thebaldgeek](https://discourse.nodered.org/u/thebaldgeek)\
**Post date:** [13 September 2019 13:18 UTC](https://discourse.nodered.org/t/tcp-receive-data-led-indicator-flip-flop/15506/1 "2019-09-13T13:18:56Z")

</div>

I have two TCP nodes that are getting data from other Node-RED instances, that works fine.  
What I am looking for is an LED (or some indicator) of where the data is coming from.  
Here is a screen shot to help.....

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/2X/5/5020c073fe5b38a2dd59ac91b46fe48e12635fcf.png)

I would like 2 LED's. One for port A, one for port B.  
When data comes from port A, LED A turns on. When data comes from port B, LED B turns on and LED A turns off.  
If another payload comes from Port B, nothing changes.

I think I need a binary flip-flop, but when I tried to make one, I had an infinite feedback loop and crashed Node-RED, so I clearly need a little help.....

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<div class="post-metadata">

**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [13 September 2019 13:26 UTC](https://discourse.nodered.org/t/tcp-receive-data-led-indicator-flip-flop/15506/2 "2019-09-13T13:26:21Z")

</div>

sort of like

```auto
[{"id":"9a84e7e3.a615a8","type":"tcp in","z":"3658255b.2041aa","name":"","server":"server","host":"","port":"5555","datamode":"stream","datatype":"buffer","newline":"","topic":"","base64":false,"x":210,"y":1280,"wires":[["293bfc05.dbfea4","a3715465.d77148"]]},{"id":"293bfc05.dbfea4","type":"change","z":"3658255b.2041aa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":1280,"wires":[["10ede147.9458ff"]]},{"id":"10ede147.9458ff","type":"ui_led","z":"3658255b.2041aa","group":"1e4b8483.ea6fab","order":7,"width":0,"height":0,"label":"","labelPlacement":"left","labelAlignment":"left","colorForValue":[{"color":"gray","value":"false","valueType":"bool"},{"color":"green","value":"true","valueType":"bool"}],"name":"","x":650,"y":1280,"wires":[]},{"id":"a3715465.d77148","type":"change","z":"3658255b.2041aa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"false","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":1320,"wires":[["ecee025e.d47ad"]]},{"id":"ecee025e.d47ad","type":"ui_led","z":"3658255b.2041aa","group":"1e4b8483.ea6fab","order":7,"width":0,"height":0,"label":"","labelPlacement":"left","labelAlignment":"left","colorForValue":[{"color":"gray","value":"false","valueType":"bool"},{"color":"red","value":"true","valueType":"bool"}],"name":"","x":650,"y":1320,"wires":[]},{"id":"41f2c7a4.0206f8","type":"tcp in","z":"3658255b.2041aa","name":"","server":"server","host":"","port":"5556","datamode":"stream","datatype":"buffer","newline":"","topic":"","base64":false,"x":220,"y":1380,"wires":[["e4c1be4.280934","8b4e898a.559598"]]},{"id":"e4c1be4.280934","type":"change","z":"3658255b.2041aa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":430,"y":1380,"wires":[["ecee025e.d47ad"]]},{"id":"8b4e898a.559598","type":"change","z":"3658255b.2041aa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"false","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":430,"y":1420,"wires":[["10ede147.9458ff"]]},{"id":"6b2d1ae5.460274","type":"inject","z":"3658255b.2041aa","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":200,"y":1320,"wires":[["293bfc05.dbfea4","a3715465.d77148"]]},{"id":"d5cc1526.4caaf8","type":"inject","z":"3658255b.2041aa","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":220,"y":1420,"wires":[["e4c1be4.280934","8b4e898a.559598"]]},{"id":"1e4b8483.ea6fab","type":"ui_group","z":"","name":"LED example","tab":"28e3359c.db4eaa","order":1,"disp":true,"width":"6","collapse":false},{"id":"28e3359c.db4eaa","type":"ui_tab","z":"","name":"Home","icon":"dashboard","order":1,"disabled":false,"hidden":false}]

```

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/2X/c/c1e236d305ae49f874f31258ca005043ade8d09b.png)

---

<div class="post-metadata">

**Author:** ![thebaldgeek](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/thebaldgeek/32/93523_2.png) [@thebaldgeek](https://discourse.nodered.org/u/thebaldgeek)\
**Post date:** [13 September 2019 13:38 UTC](https://discourse.nodered.org/t/tcp-receive-data-led-indicator-flip-flop/15506/3 "2019-09-13T13:38:24Z")

</div>

Thanks so much @dceejay  
I never would have come up with that. I was too obsessed with logic gates.  
Your way is much clearer.  
Cheers.