Serial on Raspberry PI3B+ don't work

General
1

Hello everyone,

after some hours to try everything I found on forum I'm finished to create this topic.
I try to send a string through the serial port of my Raspberry PI3B+ with node-red.

Even I don't hace the correct sentence on the receiver (just a configuration), it works with the simple bash command : echo "Hello" > /dev/ttyAMA0. It works too with /dev/serial0 then the configuiration is OK.

I added a inject node with "hello" and a serial out node to serrial port.
I tried with /dev/serial0 without error but not the slightest character on the receiver.
And with /dev/ttyAMA0 it crashes node-red. Need to delete the node in flows.json file and reboot.

I tried with serial control node and it seems to work: no error and node "connected" with the right parameters.
All other development works fine.

Is someone can help me please?

Thanks a lot.

PS : installation in docker with following version
debian 10 (buster)
node-red 3.1.5
node-red-node-serialport 2.0.2
rebuild --build-from-source done too.

2

Hi, Welcome to the forum.

Have a look at this topic,

3

As you are using Docker, have you enabled the serial port in your Docker environment?

4

Hello,
thanks a lot for your response, i try this this weekend and will give you a feedback.

Regards

5

Finally, I found some minutes to test your proposition.

I enable the serial port in docker.
The result is no crash of node-red when i inject a string in "serial out". Good evolution.

But,

  • the command echo "hello" > /dev/serial0 is already OK : data received
  • the injection of "hello" in "serial out" node in node-red is NOK : no data received

Other ideas?

Thanks.

6

You might need to check the node settings to make sure they match the actual settings of the serial port.

Also, I'm surprised that worked because I'd expect Node-RED to have locked access to the port. Though I'm not 100% sure to be honest.

Have you checked in the dmesg log to see if there is an error? Also, have you checked the Node-RED startup log for an error?

7

all settings checked.
No message in dmesg.
No message in node red console (just inject successfully on top)
How can I access to node-red log please?

8

I don't have the "Connected" at the bottom of the node "serial out" but it appears on the "config" node.

9

Sorry, the ttyAMA0 doesn't work... even after @TotallyInformation proposal to enable serial port in docker.
I don't know how verify the serial port is really enable.

10

Hello,

I found the solution there: https://community.gladysassistant.com/t/node-red-mise-a-jour-de-la-palette-node-red-node-serialport-1-0-1-fait-planter-le-docker-node-red/7154/18

It's in French but the solution is just to rebuild the node-red-node-serialport.
It doesn't work with the initial build.

sorry for disturbing you
have a nice day

11

Serial requires a compiled C/C++ component. In keeping with all Node.js apps that interface with C/C++ components, when changing major versions of Node.js, you should rebuild the dependencies with npm rebuild or bad-things™️ will happen.

So do remember to do that when node.js major versions change. Other nodes of similar ilk will be SQLite, bluetooth, and quite a number of others. Safest simply to build rebuilds into your process when you upgrade to a new major version of Node.JS.