# node-red-contrib-socketcan ![socketcan](./images/node-red-contrib-socketcan.png) This is a couple of nodes to read CAN frames from and send CAN frames to a CAN bus using socketcan. [Socketcan](https://www.kernel.org/doc/Documentation/networking/can.txt) is the standard CAN subsystem on Linux. Socketcan is not available on Windows. This project is inspired by [node-red-contrib-canbus](https://flows.nodered.org/node/node-red-contrib-canbus) (Rajesh Sola ) which almost did what I needed but not quite. [can-utils](https://github.com/linux-can/can-utils) is a good set of companion tools when working with socketcan. Some info about bringing a (virtual) CAN interface up is [here](https://elinux.org/Bringing_CAN_interface_up). If you need real CAN hardware [TouCAN](https://www.rusoku.com/products) is a good choice (no affiliation except for using it myself). This project is part of the VSCP ([https://www.vscp.org](https://www.vscp.org)) project. ## Install Go to node-red folder and ```bash npm install node-red-contrib-socketcan ``` or install in node-red palette. ## Sending CAN frames ![socketcan-in](./images/socketcan-in.png) socketcan-in node is provided for sending CAN frames. You can send standard or extended id frames, FD frames are supported. Set up the interface to some real CAN hardware or use a virtual interface. ### payload #### Object/JSON formated message The CAN message is defined as a JSON object with the following payload format ```json { "canfd":false, "ext":false, "rtr":false, "canid":123, "dlc":5, "data":[1,2,3,4,5] } ``` * canfd - Marks the frame as a CAN-FD frame. * ext - Marks the message as an extended id message. * rtr - The message is a remote transmission request. No data should be specified in this case (set to null). * canid - The canid for the CAN message. Must be less then 0x7ff for a standard CAN message. * dlc - Number of databytes, 0-64. * data - An array, comma separated list or buffer with data bytes. Set to null if no data. #### String formated messages The CAN message is defined as a string with the following payload format ``` #{R|data} ``` * canid - Less than 0x7ff and with less than three digits for a standard id. Always defined in hex format. * data - The data part for the can frame. Always in hex format. * R - Specifies a remote transmission request frame. ##### Examples ``` 123#DEADBEEF - standard frame 5AA# - Standard frame no data 1F334455#1122334455667788 - extended frame 123#R - for remote transmission request. 123## - FD frame no data 123##AA - FD frame standard ``` ## Receiving CAN frames ![socketcan-out](./images/socketcan-out.png) socketcan-out node is provided for receiving CAN frames. You can receive standard or extended CAN id frames. Set up the interface to some real CAN hardware or use a virtual interface. ### Payload The payload is always a Javascript object on the following form. { timestamp: 1552881174, ext: 0, rtr: 0, canid: 123, dlc: 5, data: [1,2,3,4,5] } * canid - The standard or extended can id. * ext - Set to true if this is a extended id frame. False otherwise. * rtr - Specifies a remote transmission request frame if set to true. * dlc - Number of databytes. * data - An array with data or null or an empty array if no data. * rawData - Holds frame data on buffer format for convinience. The timestamp (in microseconds) is generated by the node if not supplied by the interface. ## Example flow Enable a virtual CAN interface with ```bash $ modprobe vcan $ sudo ip link add dev vcan0 type vcan $ sudo ip link set up vcan0 ``` install can-utils with ```bash sudo apt install can-utils ``` Receive CAN frames with ```bash candump vcan0 ``` Send CAN frames with ```bash cansend vcan0 123#1122334455 ``` Use this flow to interact with the other tools. ```json [ { "id": "829af3ee.a57c1", "type": "tab", "label": "Flow 1", "disabled": false, "info": "" }, { "id": "b2855d5b.1215c8", "type": "socketcan-config", "z": "", "interface": "can0" }, { "id": "38e8307.1653f5", "type": "socketcan-config", "z": "", "interface": "vcan0" }, { "id": "7b24a62e.8f5458", "type": "debug", "z": "829af3ee.a57c1", "name": "", "active": true, "tosidebar": true, "console": false, "tostatus": false, "complete": "false", "x": 350, "y": 360, "wires": [] }, { "id": "5f671b29.cd24bc", "type": "socketcan-out", "z": "829af3ee.a57c1", "name": "socketcan-out", "config": "38e8307.1653f5", "x": 150, "y": 360, "wires": [ [ "7b24a62e.8f5458" ] ] }, { "id": "caba412f.047b2", "type": "socketcan-in", "z": "829af3ee.a57c1", "name": "socketcan-out", "config": "38e8307.1653f5", "x": 360, "y": 120, "wires": [] }, { "id": "a64240cb.3f0788", "type": "inject", "z": "829af3ee.a57c1", "name": "Send object - std", "topic": "", "payload": "{\"ext\":false,\"canid\":123,\"dlc\":5,\"data\":[1,2,3,4,5]}", "payloadType": "json", "repeat": "", "crontab": "", "once": false, "onceDelay": 0.1, "x": 160, "y": 120, "wires": [ [ "caba412f.047b2" ] ] }, { "id": "3ff96369.ef6f5c", "type": "inject", "z": "829af3ee.a57c1", "name": "Send string - std", "topic": "", "payload": "123#00112233", "payloadType": "str", "repeat": "", "crontab": "", "once": false, "onceDelay": 0.1, "x": 160, "y": 200, "wires": [ [ "caba412f.047b2" ] ] }, { "id": "6879c00a.5edb68", "type": "inject", "z": "829af3ee.a57c1", "name": "Send string - ext", "topic": "", "payload": "1F334455#1122334455667788", "payloadType": "str", "repeat": "", "crontab": "", "once": false, "onceDelay": 0.1, "x": 160, "y": 240, "wires": [ [ "caba412f.047b2" ] ] }, { "id": "1ee3b274.4cb8fe", "type": "inject", "z": "829af3ee.a57c1", "name": "Send object - ext", "topic": "", "payload": "{\"ext\":true,\"canid\":32278,\"dlc\":5,\"data\":[1,2,3,4,5]}", "payloadType": "json", "repeat": "", "crontab": "", "once": false, "onceDelay": 0.1, "x": 160, "y": 160, "wires": [ [ "caba412f.047b2" ] ] }, { "id": "391a4c45.7acd8c", "type": "comment", "z": "829af3ee.a57c1", "name": "Send CAN frames in using different payloads on VCAN0", "info": "", "x": 260, "y": 80, "wires": [] }, { "id": "912f9928.da2758", "type": "comment", "z": "829af3ee.a57c1", "name": "Receiove CAN data from interface VCAN0", "info": "", "x": 220, "y": 320, "wires": [] } ] ``` ## Debugging It is possible to get extra debug information from the nodes in this package. Issue ``` bash export NODE_DEBUG=socketcan-in ``` before starting node-red to get extra debug info for the socketcan-in node. Issue ``` bash export NODE_DEBUG=socketcan-out ``` before starting node-red to get extra debug info for the socketcan-out node. Issue ``` bash export NODE_DEBUG=socketcan-in socketcan-out ``` before starting node-red to get extra debug info for both the socketcan-in and socketcan-out node. --- Copyright © 2020-2024 Ake Hedman, Grodans Paradis AB - MIT License