# Switch only on true for a change-over of the output
**URL:** https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021
**Category:** General
**Created:** [14 October 2022 09:07 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021 "2022-10-14T09:07:54Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Sweetpeet](https://discourse.nodered.org/u/Sweetpeet)
#### Post date: [14 October 2022 09:07 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/1 "2022-10-14T09:07:54Z")
Hi There, I'm quite new to NR and I'm trying to use a pulse switch on the GPIO board to output a JSON dimmer value to my dimmers. What I want is: On the first push of the switch the output is 1 and on the second push of the switch the output is zero. I sound simple but I can't make it work.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [14 October 2022 09:33 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/2 "2022-10-14T09:33:14Z")
Hi and welcome to the forum.
There is a `toggle` switch node that would get around this problem. 😉
But I'm guessing there will be more than 1 GUI button to control things.
The `pulse switch`. As is `button`?
Going to the next step you will need to use the thing called `context`.
This will suffice but also has a bit of _extra_ code in it also.
It goes in a `function` node.
```auto
var x = context.get("counter") || 0;
if (msg.payload == 0)
{
context.set("counter",0);
msg.payload = 0;
return msg;
}
if (msg.payload == 1)
{
context.set("counter",1);
msg.payload = 1;
return msg;
}
if (x === 0)
{
msg.payload = 1;
} else
if (x === 1)
{
msg.payload = 0;
}
x = (x + 1) % 2;
context.set("counter",x);
return msg;
```
The _extra_ part is that normally you send _something_ as the `msg.payload` to toggle the output.
But if you send a `0` or `1` it forces the output to be either OFF or ON.
So as long as you don't send a `msg.payload` of either `0` or `1` it should work fine.
Oh, you will/may have to edit/change what is sent for the `ON` and `OFF` conditions.
You haven't said what you send to the GPIO pin.
---
### Author:  [@Sweetpeet](https://discourse.nodered.org/u/Sweetpeet)
#### Post date: [14 October 2022 10:06 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/3 "2022-10-14T10:06:18Z")
Thanks for your reply and I think I almost there but whenI use the toggle it goes ON and OFF. The functions output is then 1 or 0 and it doesn't only change when the toggle goes to ON. Do I miss something?
---
### Author:  [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)
#### Post date: [14 October 2022 10:12 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/4 "2022-10-14T10:12:54Z")
Can you state what the input value is from your GPIO and what output you expect?
e.g.
- is the action of the switch momentary (i.e. does the GPIO send a `1` followed by `0`? does the GPIO send a `0` followed by `1`? )
- is the action of the switch a toggle? (i.e. does first press send a `1` and second press send a `0`?)
- What do you want so be the result of the flow - send strings like "ON" and "OFF"? send `true` / `false`? Send `1` / `0` ?
In other words, please be specific.
---
### Author:  [@E1cid](https://discourse.nodered.org/u/E1cid)
#### Post date: [14 October 2022 13:21 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/5 "2022-10-14T13:21:30Z")
This should work, each press toggles output 1 then 0 then 1 then 0
```auto
[{"id":"8a9d0c48438c6c7d","type":"inject","z":"366a43adb328cf95","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1","payloadType":"num","x":250,"y":980,"wires":[["c0a46a18812e14e5"]]},{"id":"c0a46a18812e14e5","type":"change","z":"366a43adb328cf95","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"switch_toggle","tot":"flow"},{"t":"set","p":"payload","pt":"msg","to":"$$.payload = 1 ? 0 : 1","tot":"jsonata"},{"t":"set","p":"switch_toggle","pt":"flow","to":"payload","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":980,"wires":[["afed0c6bfa9fbd91"]]},{"id":"afed0c6bfa9fbd91","type":"debug","z":"366a43adb328cf95","name":"debug 93","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":600,"y":980,"wires":[]}]
```
[edit] misread, edited for use with a input of a gpio.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [14 October 2022 19:39 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/6 "2022-10-14T19:39:31Z")
I'm not sure what you mean by your reply.
But how the output works:
(From the code I posted)
```auto
if (x === 0)
{
msg.payload = 1; // This is the payload for ON
} else
if (x === 1)
{
msg.payload = 0; // This is the payload for OFF
}
```
So you edit those two lines to be what you want to send to the GPIO pin.
Also: To clarify.
You only send something like `X` into the `function` node (well: that's what I use) and the ouput sends alternate `0` and `1` each time you send `X` into the node.
**IF** you want to force the output, you send a `0` or `1` to force it OFF or ON respectively.
---
### Author:  [@Sweetpeet](https://discourse.nodered.org/u/Sweetpeet)
#### Post date: [16 October 2022 09:25 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/7 "2022-10-16T09:25:51Z")
> [@E1cid](#):
>
> `[{"id":"8a9d0c48438c6c7d","type":"inject","z":"366a43adb328cf95","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1","payloadType":"num","x":250,"y":980,"wires":[["c0a46a18812e14e5"]]},{"id":"c0a46a18812e14e5","type":"change","z":"366a43adb328cf95","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"switch_toggle","tot":"flow"},{"t":"set","p":"payload","pt":"msg","to":"$.payload = 1 ? 0 : 1","tot":"jsonata"},{"t":"set","p":"switch_toggle","pt":"flow","to":"payload","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":980,"wires":[["afed0c6bfa9fbd91"]]},{"id":"afed0c6bfa9fbd91","type":"debug","z":"366a43adb328cf95","name":"debug 93","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":600,"y":980,"wires":[]}]`
Yes, thanks that works!
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [30 October 2022 09:26 UTC](https://discourse.nodered.org/t/switch-only-on-true-for-a-change-over-of-the-output/69021/8 "2022-10-30T09:26:32Z")
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.