node-red-contrib-xkeys_setunitid

This is another in a collection of Node-RED nodes which enable access to X-keys physical devices using Dynamic Control Data Protocol (DCDP).

A dedicated Node-RED node for each X-key event of interest (button, jog, joystick, etc.) will communicate, using MQTT, with a lightweight DCDP server, whose sole purpose is to mediate access to any physically attached X-keys devices.

Most X_keys devices ship with a default Unit ID of 0. This xkeys_setunitid node enables specific X-keys devices to change the Unit ID.

Installation

Please note that this xkeys_setunitid node runs correctly only on version 4 of the Raspberry Pi - USB hardware on previous versions is insufficient for this node to run cleanly. Success on ordinary computers depends on the age of the USB hardware being used.

This node requires dcdp-server version 0.1.1 to be running. Please follow the instructions at the dcdp-server development repository to install it or, to upgrade an existing installation, see the dcdp-server upgrade instructions.

The node-red-contrib-xkeys_setunitid node itself is best installed from Node-RED's Palette manager. Go to the Palette manager's Install tab and search for node-red-contrib-xkeys_setunitid; then Install it once found. If not found, press the Refresh module list button (two semicircular arrows) and search again.

When installed, a new xk Set Unit ID node will be found in the palette tab in the dedicated Xkeys category.

Usage

The node's configuration editor must be used to explicitly set the target X-keys device, as well as both current and proposed new Unit IDs of the device. The node's built in button can then be used to activate the change of Unit ID, at which time the targeted device will be rediscovered with its new Unit ID.

An example flow is provided in the examples directory to demonstrate how the xkeys_setunitid node could be used.

In this example, a Debug node showing the msg.payload of an xkeys_button enables accurate discovery of the current Unit ID of the target device. This, along with the new Unit ID, needs to be set in the xkeys_setunitid configuration editor. When an attached device, Unit ID and new Unit ID have been configured correctly and deployed, the node will display a button. Clicking the xkeys_setunitid button executes the change of the device Unit ID.

On modern hardware e.g. RPI4, the change will be discovered automatically resulting in the xkeys_setunitid node's status changing to disconnected (since it is configured with the device's old Unit ID). On older hardware, the device may need to be replugged for the change in Unit ID to be discvovered.

Issues

When configuring the node, a drop down list of possible devices shoud be available. If not, instead displaying just a note to Press Deploy button to see device list, first follow that advice. If that is unsuccessful (still no list of possible devices), then check the status of the dcdp-server by running the command sudo systemctl status dcdp-server in a terminal. Typical output of a normally running dcdp-server will be:

pi@pi3b:~ $ sudo systemctl status dcdp-server
● dcdp-server.service - Run dcdp-server as background service
Loaded: loaded (/etc/systemd/system/dcdp-server.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-10-14 09:31:55 AEST; 23h ago

whereas a non-running dcdp-server will show something like:

pi@pi3b:~ $ sudo systemctl status dcdp-server
● dcdp-server.service - Run dcdp-server as background service
Loaded: loaded (/etc/systemd/system/dcdp-server.service; enabled; vendor preset: enabled)
Active: failed (Result: timeout) since Fri 2021-10-15 08:41:37 AEST; 19s ago

If necessary, (re)start the dcdp-server with sudo systemctl restart dcdp-server

Authors and acknowledgment

Many thanks to P.I. Engineering for financial support and donation of several X-keys devices for development and testing.

License

MIT