# Serial Port Control
**URL:** https://discourse.nodered.org/t/serial-port-control/14894
**Category:** General
**Created:** [29 August 2019 10:47 UTC](https://discourse.nodered.org/t/serial-port-control/14894 "2019-08-29T10:47:01Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [29 August 2019 10:47 UTC](https://discourse.nodered.org/t/serial-port-control/14894/1 "2019-08-29T10:47:02Z")
Hi everyone,
I'm having trouble using the node-red-node-serialport node at 0.8.3 on Node-RED 0.20.5
I try to connect a device (Multiverter) with a usb-serial adapter. With minicom I can control the device at /dev/ttyUSB0 with 115200-8N1 and Hardware- and Software Flow Control disabled (should be for the device).
I see in Node-RED the tag "connected" under the serial node and "disconnected" when I pull out the USB connector but when I try to send a command as payload it just times out.
I already got something out of the serial input node after I sent a command into the device via minicom.
As far as I analyzed the problem the only difference to minicom is Hardware and Software Flow Control which I can't find how to disable in Node-RED. Any advice over there?
I don't think it would be helpful but here's my flow:
```auto
[{"id":"144b9afa.7ca115","type":"tab","label":"Multiverter","disabled":false,"info":""},{"id":"af5f1367.a5fb8","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"help","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":150,"y":480,"wires":[["9255fcc4.f772e","66aaf885.659488"]]},{"id":"640ccb7b.19dfc4","type":"debug","z":"144b9afa.7ca115","name":"serial return","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":670,"y":460,"wires":[]},{"id":"9255fcc4.f772e","type":"serial request","z":"144b9afa.7ca115","name":"","serial":"92c4fb6c.c8bcd8","x":520,"y":320,"wires":[["640ccb7b.19dfc4"]]},{"id":"66aaf885.659488","type":"debug","z":"144b9afa.7ca115","name":"Sent","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":430,"y":420,"wires":[]},{"id":"92c4fb6c.c8bcd8","type":"serial-port","z":"","serialport":"/dev/ttyUSB0","serialbaud":"115200","databits":"8","parity":"none","stopbits":"1","waitfor":"","newline":"\\n","bin":"false","out":"char","addchar":"","responsetimeout":"3000"}]
```
Cheers!
---
### Author:  [@ukmoose](https://discourse.nodered.org/u/ukmoose)
#### Post date: [29 August 2019 10:58 UTC](https://discourse.nodered.org/t/serial-port-control/14894/2 "2019-08-29T10:58:39Z")
what version of Nodejs are you using?
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [29 August 2019 11:20 UTC](https://discourse.nodered.org/t/serial-port-control/14894/3 "2019-08-29T11:20:44Z")
Node-RED does not enable flow control.
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [29 August 2019 11:34 UTC](https://discourse.nodered.org/t/serial-port-control/14894/4 "2019-08-29T11:34:48Z")
Node.js is on Version 10.16.3
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [29 August 2019 11:46 UTC](https://discourse.nodered.org/t/serial-port-control/14894/5 "2019-08-29T11:46:46Z")
you may need to add "\r" or "\n" to the end of any command you send
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [29 August 2019 11:50 UTC](https://discourse.nodered.org/t/serial-port-control/14894/6 "2019-08-29T11:50:08Z")
Tried that, does sadly not help.
I thought of that because in minicom I (obviously) have to hit return, but that doesn't help here.
```auto
[{"id":"144b9afa.7ca115","type":"tab","label":"Multiverter","disabled":false,"info":""},{"id":"af5f1367.a5fb8","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"help \n","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":150,"y":480,"wires":[["9255fcc4.f772e","66aaf885.659488"]]},{"id":"640ccb7b.19dfc4","type":"debug","z":"144b9afa.7ca115","name":"serial return","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":670,"y":460,"wires":[]},{"id":"9255fcc4.f772e","type":"serial request","z":"144b9afa.7ca115","name":"","serial":"92c4fb6c.c8bcd8","x":490,"y":320,"wires":[["640ccb7b.19dfc4"]]},{"id":"66aaf885.659488","type":"debug","z":"144b9afa.7ca115","name":"Sent","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":430,"y":420,"wires":[]},{"id":"cbe578b1.9c4c88","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"help \r","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":150,"y":420,"wires":[["9255fcc4.f772e","66aaf885.659488"]]},{"id":"92c4fb6c.c8bcd8","type":"serial-port","z":"","serialport":"/dev/ttyUSB0","serialbaud":"115200","databits":"8","parity":"none","stopbits":"1","waitfor":"","newline":"\\n","bin":"false","out":"char","addchar":"","responsetimeout":"3000"}]
```
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [29 August 2019 11:53 UTC](https://discourse.nodered.org/t/serial-port-control/14894/7 "2019-08-29T11:53:41Z")
Hi - well neither of those will work... for as start it is \r not /r.
second if you use an inject like that it will send the string /r (or \r) and not the return character. First you should try the serial config -
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [29 August 2019 11:57 UTC](https://discourse.nodered.org/t/serial-port-control/14894/8 "2019-08-29T11:57:18Z")
Yeah I realized the wrong slash after I exported it for here.
I tried it in the serial config though but it wont work either.
Now that's what I did this time.
```auto
[{"id":"4d794a3.d4b52b4","type":"serial request","z":"23060d0.15a20f4","name":"","serial":"92c4fb6c.c8bcd8","x":490,"y":320,"wires":[["d0ee70a.0313b9"]]},{"id":"92c4fb6c.c8bcd8","type":"serial-port","z":"","serialport":"/dev/ttyUSB0","serialbaud":"115200","databits":"8","parity":"none","stopbits":"1","waitfor":"","newline":"\\n","bin":"false","out":"char","addchar":"\\n","responsetimeout":"3000"}]
```
---
### Author:  [@kocherjj](https://discourse.nodered.org/u/kocherjj)
#### Post date: [30 August 2019 00:25 UTC](https://discourse.nodered.org/t/serial-port-control/14894/9 "2019-08-30T00:25:00Z")
I just ran into this issue the other day. I couldn't get serial control to work for a particular device that needed a newline at the end of each command.
Setting the Serial Out Node to add the "\n" character to output messages did not work. I confirmed by connecting the output of the node to a serial port on my laptop and reading the output in real time. It simply appended the text to the String.
For example, if I sent a command that reads "POWR 1", and then a command that reads "VOLM 21" in the picocom terminal this came through as:
POWR 1\nVOLM 21\n
So instead I added this in a function node before the serial out node:
msg.payload = msg.payload+"\n"
return msg;
This gives me :
POWR 1
------------VOLM 21
(The hyphens are in place of white spaces because the forum will not display it properly otherwise)
So the serial node is not adding the character as I would have expected but the function node does. Because I am OCD I changed it to:
msg.payload = msg.payload+"\r"+"\n"
return msg;
Now I get:
POWR 1
VOLM 21
It's working fine this way. Might be worth a try.
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [30 August 2019 10:58 UTC](https://discourse.nodered.org/t/serial-port-control/14894/10 "2019-08-30T10:58:13Z")
You are my man. That's working for me fine.
I felt like that could be the problem for days because it didn't seem to send the command properly since it just timed down.
So really thank you, that's awesome!
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [30 August 2019 11:40 UTC](https://discourse.nodered.org/t/serial-port-control/14894/11 "2019-08-30T11:40:21Z")
just for clarity - was it the "\r" that worked - or did it need both +"\r\n" ?
(as the former should have worked inside the serial node config... - so will need to be investigated)
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [30 August 2019 12:03 UTC](https://discourse.nodered.org/t/serial-port-control/14894/12 "2019-08-30T12:03:49Z")
Actually - yes it looks like a bug... now fixed in version 0.8.5 on npm.
in the config adding \r should now work... (without need for function node) - would be great if you can confirm. Thanks.
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [30 August 2019 12:36 UTC](https://discourse.nodered.org/t/serial-port-control/14894/13 "2019-08-30T12:36:48Z")
I used the \r to get it working!
Will confirm the 0.8.5 in a minute, when i got time for it!
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [30 August 2019 12:49 UTC](https://discourse.nodered.org/t/serial-port-control/14894/14 "2019-08-30T12:49:55Z")
So: I updated the serial node.
When I connect the inject node directly to the serial node where I added the \r (bypassing the function node) they stop timeouting like before.
```auto
[{"id":"144b9afa.7ca115","type":"tab","label":"Multiverter","disabled":false,"info":""},{"id":"af5f1367.a5fb8","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"preset recall 3","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":170,"y":480,"wires":[["e562c5d6.aef208"]]},{"id":"9255fcc4.f772e","type":"serial request","z":"144b9afa.7ca115","name":"","serial":"92c4fb6c.c8bcd8","x":490,"y":280,"wires":[["b8a16458.0f82a8"]]},{"id":"66aaf885.659488","type":"debug","z":"144b9afa.7ca115","name":"Sent","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":450,"y":340,"wires":[]},{"id":"cbe578b1.9c4c88","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"help","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":150,"y":440,"wires":[["e562c5d6.aef208"]]},{"id":"461da1a2.ae5b7","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"preset recall 1","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":170,"y":520,"wires":[["9255fcc4.f772e"]]},{"id":"b603dddf.b1375","type":"inject","z":"144b9afa.7ca115","name":"","topic":"","payload":"volume 15","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":160,"y":560,"wires":[["9255fcc4.f772e"]]},{"id":"b8a16458.0f82a8","type":"debug","z":"144b9afa.7ca115","name":"return","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":870,"y":300,"wires":[]},{"id":"990b57a7.1b54a8","type":"udp in","z":"144b9afa.7ca115","name":"","iface":"","port":"34421","ipv":"udp4","multicast":"false","group":"","datatype":"utf8","x":160,"y":220,"wires":[["e562c5d6.aef208"]]},{"id":"e562c5d6.aef208","type":"function","z":"144b9afa.7ca115","name":"","func":"msg.payload = msg.payload+\"\\r\"\nreturn msg;","outputs":1,"noerr":0,"x":370,"y":180,"wires":[["9255fcc4.f772e","66aaf885.659488"]]},{"id":"92c4fb6c.c8bcd8","type":"serial-port","z":"","serialport":"/dev/ttyUSB0","serialbaud":"115200","databits":"8","parity":"none","stopbits":"1","waitfor":"","newline":"300","bin":"false","out":"time","addchar":"\\r","responsetimeout":"300"}]
```
That's my flow now.
While the upper two injects work flawless the lower two just timeout like before (but work if I connect them back to the function node of course).
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [30 August 2019 13:48 UTC](https://discourse.nodered.org/t/serial-port-control/14894/15 "2019-08-30T13:48:14Z")
Thanks for testing.. ok ... 0.8.6... now there to try...
apologies for half a fix.
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [30 August 2019 14:35 UTC](https://discourse.nodered.org/t/serial-port-control/14894/16 "2019-08-30T14:35:56Z")
Yip that works! Thanks for helping out!
---
### Author:  [@dceejay](https://discourse.nodered.org/u/dceejay)
#### Post date: [30 August 2019 14:37 UTC](https://discourse.nodered.org/t/serial-port-control/14894/17 "2019-08-30T14:37:52Z")
Thanks for bringing that to our attention.
---
### Author:  [@32Domi](https://discourse.nodered.org/u/32Domi)
#### Post date: [30 August 2019 14:40 UTC](https://discourse.nodered.org/t/serial-port-control/14894/18 "2019-08-30T14:40:41Z")
Tried 4 days thinking it's about me beeing not firm with node-red right now but I'm glad that it wasn't me beeing dumb or so. 😛
---
### Author:  [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)
#### Post date: [2 September 2019 07:49 UTC](https://discourse.nodered.org/t/serial-port-control/14894/19 "2019-09-02T07:49:03Z")
> [@kocherjj](#):
>
> The hyphens are in place of white spaces because the forum will not display it properly otherwise
Wrap things like that in triple back-ticks or use the "preformated text" icon in the editor toolbar.
---
### Author:  [@jeffreys](https://discourse.nodered.org/u/jeffreys)
#### Post date: [1 July 2020 18:36 UTC](https://discourse.nodered.org/t/serial-port-control/14894/20 "2020-07-01T18:36:19Z")
Im trying the /r after i send a hex buffer and i get the following error..
TypeError [ERR\_INVALID\_ARG\_TYPE]: The "list[1]" argument must be one of type Array, Buffer, or Uint8Array. Received type string
Anyone know what I am doing wrong here?
```auto
[{"id":"f042e293.4bd948","type":"tab","label":"Flow 5","disabled":false,"info":""},{"id":"be2f3e94.08e27","type":"serial out","z":"f042e293.4bd948","name":"","serial":"6316eb55.80e3a4","x":690,"y":280,"wires":[]},{"id":"2d54136f.d45514","type":"inject","z":"f042e293.4bd948","name":"Set to EOL","topic":"","payload":"[\"0x02\",\"0x01\",\"0x01\",\"0x41\",\"0x40\",\"0x00\",\"0x08\",\"0x41\",\"0x1E\",\"0x90\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x82\",\"0x03\",\"0x45\"]","payloadType":"bin","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":440,"y":280,"wires":[["52f778b2.1c696"]]},{"id":"b9937022.701d4","type":"inject","z":"f042e293.4bd948","name":"Set Normal","topic":"","payload":"[\"0x02\",\"0x01\",\"0x01\",\"0x41\",\"0x40\",\"0x00\",\"0x08\",\"0x41\",\"0x1E\",\"0x17\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x83\",\"0x03\",\"0xC3\"]","payloadType":"bin","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":430,"y":320,"wires":[["be2f3e94.08e27"]]},{"id":"43164026.d98908","type":"inject","z":"f042e293.4bd948","name":"MainBoard-Relay1Off","topic":"","payload":"[\"0x02\",\"0x01\",\"0x01\",\"0x41\",\"0x40\",\"0x00\",\"0x22\",\"0x20\",\"0x12\",\"0x00\",\"0x5A\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x03\",\"0x4A\"]","payloadType":"bin","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":400,"y":420,"wires":[["be2f3e94.08e27"]]},{"id":"9f0a0b28.d830b","type":"inject","z":"f042e293.4bd948","name":"MainBoard-Relay2On","topic":"","payload":"[\"0x02\",\"0x01\",\"0x01\",\"0x41\",\"0x40\",\"0x00\",\"0x22\",\"0x20\",\"0x12\",\"0x00\",\"0x5A\",\"0x00\",\"0x00\",\"0x00\",\"0x01\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x03\",\"0x4B\"]","payloadType":"bin","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":400,"y":460,"wires":[["be2f3e94.08e27"]]},{"id":"47cfc409.596604","type":"inject","z":"f042e293.4bd948","name":"MainBoard-Relay1On","topic":"","payload":"[\"0x02\",\"0x01\",\"0x01\",\"0x41\",\"0x40\",\"0x00\",\"0x22\",\"0x20\",\"0x12\",\"0x00\",\"0x5A\",\"0x00\",\"0x01\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x00\",\"0x03\",\"0x4B\"]","payloadType":"bin","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":400,"y":380,"wires":[["52f778b2.1c696"]]},{"id":"13c53829.be0b88","type":"inject","z":"f042e293.4bd948","name":"fake mqtt Set to end of line mode","topic":"","payload":"0201 0141 4000 0841 1E90 0000 0000 8203 45","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":500,"wires":[["d12565c9.4d6cf8"]]},{"id":"d12565c9.4d6cf8","type":"function","z":"f042e293.4bd948","name":"Hex string to Hex buffer","func":"msg.oldPayload = msg.payload; //save it for later debugging\nvar noSpaces = msg.payload.replace(/ /g, '');// remove spaces\nmsg.payload = Buffer.from(noSpaces, \"hex\"); //convert to buffer\nreturn msg;","outputs":1,"noerr":0,"x":410,"y":520,"wires":[["be2f3e94.08e27"]]},{"id":"c8b308cb.efb1b","type":"inject","z":"f042e293.4bd948","name":"fake mqtt MainBoard-Relay1On","topic":"","payload":"0201 0141 4000 2220 1200 5A00 0100 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0003 4B","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":540,"wires":[["d12565c9.4d6cf8"]]},{"id":"52f778b2.1c696","type":"serial request","z":"f042e293.4bd948","name":"","serial":"6316eb55.80e3a4","x":690,"y":360,"wires":[["c03cb9b3.b9d49"]]},{"id":"c03cb9b3.b9d49","type":"debug","z":"f042e293.4bd948","name":"","active":true,"tosidebar":true,"console":true,"tostatus":false,"complete":"true","targetType":"full","x":870,"y":360,"wires":[]},{"id":"6316eb55.80e3a4","type":"serial-port","z":"","serialport":"/dev/ttyUSB0","serialbaud":"115200","databits":"8","parity":"none","stopbits":"1","waitfor":"","dtr":"none","rts":"none","cts":"none","dsr":"none","newline":"\\n","bin":"false","out":"char","addchar":"\\r","responsetimeout":"10000"}]
```