Tag Archives: Node-Red Scheduler

Node-Red Scheduler

I’m Peter Scargill and this is a scheduler for Node-Red (well, more of a timer really but someone surely has already used the term timer) for Node-Red which includes days and months, dawn and dusk with optional offsets and a time-out mode, You may notice this has improved since the first version – I’m learning as I go along.

Please note: This program was replaced some time ago with bigtimer – there is no down side – bigtimer is better. See https://tech.scargill.net/big-timer/

As you may know, I’m interested in using Node-Red on the Raspberry Pi (though for this purpose it could be any piece of kit) to control ESP8266 boards via a variety of mechanisms, one of them being MQTT.

Up until recently I would use a Node-Red standard  Inject function to trigger an event, lets say once a day. The Trigger function however is very limited. It does not know about months and it has no idea about concepts such as “dusk” and “dawn” which you might reasonably want to use for a porch light.

SunriseSo, I buckled down and learned how Node-Red nodes were made (with some help later from dceejay Dave and others in the googlegroups node-red group – for which I’m grateful) – and the first thing I did was to start off with the sunrise/sunset node (you’ll need that installed as I rely on one of their routines) to send the time, date, sunrise and sunset information to my boards based on longitude and latitude. In essence, in my case I use MQTT to tell boards about the time when they power up and at 12 hour intervals and in the meantime they maintain their own time in software.

However the more I get into Node-Red the more I see it doing the actual control… so the next thing I did was to sit down and wrote a node – again borrowing from the Sunrise calculations for dusk and dawn settings but gutted to actually send one of two messages (settable) to a message topic (settable and suitable for passing onto an MQTT node for example) at any given time with presets for dusk and dawn and allowing control over days and months as well as a time-out function (i.e. turn on at 10am for 5 minutes).  So a typical example might allow us to turn something on every Wednesday at dusk until midnight but only from November to January. My node of course does not actually send an MQTT message – it just passed the topic and message onto the relevant node (the MQTT node shown in purple here). You could use that message for a variety of other purposes – like sending you a tweet at regular intervals. That is so easy in Node-Red.

The code handles summer time adjustments (well, it did this time, you might want to check that very carefully). You can even offset the dusk and dawn offset times in minutes to save, say, lighting energy, I find garden lights come on WAY before you need them – hence building in the offsets.

Here’s what it all looks like.

scheduler[1]

So every minute, my node (in blue) self-triggers  (my thanks to dcjay for showing me how to add JS timers) to do it’s calculations and decide whether or not to send a message to the MQTT output node in purple (you could easily alter the code to do something other than send an MQTT output. You will notice in the image above that there are now TWO outputs.. the top output sends a message on change – i.e. when it wants to turn something on or off.. the lower output sends a simple 1 or 0 message every minute regardless – think of it as a regular status output just like the little text and icon indicator under the node itself in the picture above. In this case each output is also sending out a debug message to the debug window in green – that’s just for testing purposes.

If you double-click on my scheduler node, here’s what you get…

scheduler

 

Simple enough, give it a name (any name), on-time and off-time which includes every 15 minutes of the day and dusk and dawn dropdown options as well as timeout options for off time… then set your longitude and latitude (from Google Maps or memory if you are like that), the topic you want to send and the two messages – one to turn something on and another to turn something off. In my case I have an MQTT message system going to ESP8266 units – I’ve detailed this elsewhere in the blog.

Tick or un-tick boxes for the weekday/month combination you want. The code is checked once every minute but the top output only sends something out at power up or when the state changes.

If this isn’t powerful enough for you? – let’s say you want something to happen twice a day? – put two of them in there.

2 schedulers[4]

So – to make this work – i.e. to make your own node there are two files – and you just create a directory in your node-red/node-red-nodes folder called scheduler, dump these two files in and restart Node-Red.

The two files are the HTML file and the .JS file called scheduler.html and scheduler.js respectively.

If you make good use of this mode, a credit would be encourage me to support it.

Also if you spot any mistakes especially in the timing – or have ideas for improvement – do let me know.

The purpose for the timeout to the end time options – is so you can say for example – turn a sprinkler on every night for 5 minutes after dusk. And that’s exactly what I plan to use it for – but only in the summer months!

Attach for example an MQTT node onto the first output and put your broker details in there. The node will pick up the topic and message from my node.

And finally  – this code is deliberately NOT constantly sending out the ON instruction every minute but only when the state changes. At any time you can press the button on the left of the node to force an output of the currently relevant message.

Enough of this – here are the goods – no guarantee implied.

Some folk had issues reading the SOURCE CODE files – so I’ve put the files on Github here.. https://github.com/scargill/scheduler

This node is relatively simple but I think that’s the point. It still took me several days to get it right and I’d appreciate any testing reports.  My next job is a thermostat node and that’s coming along nicely.

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