# Display String Output
**URL:** https://discourse.nodered.org/t/display-string-output/13855
**Category:** General
**Created:** [30 July 2019 18:30 UTC](https://discourse.nodered.org/t/display-string-output/13855 "2019-07-30T18:30:01Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [30 July 2019 18:30 UTC](https://discourse.nodered.org/t/display-string-output/13855/1 "2019-07-30T18:30:01Z")
Hello!
I am trying to print a conditional statement:
```auto
var A_x = msg.payload.d.X;
var A_y = msg.payload.d.Y;
var A_z = msg.payload.d.Z;
var A_r = Math.sqrt(A_x*A_x + A_y*A_y + A_z*A_z);
if (abs( A_r_prev - A_r) > 1100) {
msg = "Passed";
}
var A_r_prev = A_r;
return msg;
```
How to I get it to print passed. Also, is this how you store the variable (A\_r\_prev) and subtract it from the current value?
---
### Author:  [@knolleary](https://discourse.nodered.org/u/knolleary)
#### Post date: [30 July 2019 18:47 UTC](https://discourse.nodered.org/t/display-string-output/13855/2 "2019-07-30T18:47:35Z")
Hi
Functions must return message objects, not plain values.
Currently, your code sets `msg` to String `"Passed"` if the condition is met and returns that. That is not the right way to do it.
You would normally set a property of `msg` before returning it...
```auto
msg.payload = "Passed";
...
return msg;
```
For storing the value of `A_r_prev` between calls to the Function, you can use Context to do that - [https://nodered.org/docs/user-guide/context](https://nodered.org/docs/user-guide/context)
```auto
// Get the current value of A_r_prev from flow context - default to 0
// if not already set
var A_r_prev = flow.get("A_r_prev") || 0;
// do your check against it etc
// Update the value in context
flow.set("A_r_prev", A_r_prev);
```
You'll also need to change the `abs(...)` call to be `Math.abs(...)` as `abs()` isn't a function in JavaScript.
---
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [30 July 2019 21:01 UTC](https://discourse.nodered.org/t/display-string-output/13855/3 "2019-07-30T21:01:28Z")
Thank you!
Unfortunately there is no output anymore; here is my updated code
```auto
var A_x = msg.payload.d.X;
var A_y = msg.payload.d.Y;
var A_z = msg.payload.d.Z;
var A_r = Math.sqrt(A_x*A_x + A_y*A_y + A_z*A_z);
var A_r_prev = flow.get("A_r_prev") || 0;
flow.set("A_r_prev", A_r_prev);
if ( math.abs(A_r - A_r_prev) > 300) {
msg.payload = "Passed";
return msg;
}
```
I would also like to implement an audio condition (in addition to the absolute value threshold, it must pass an audio decibel level threshold. How do I do that?
Thanks
---
### Author:  [@ukmoose](https://discourse.nodered.org/u/ukmoose)
#### Post date: [30 July 2019 21:13 UTC](https://discourse.nodered.org/t/display-string-output/13855/4 "2019-07-30T21:13:39Z")
Step 1 get what you currently have working before you make it more complex.
Look at the Logging Events and handling errors sections of this page from the docs.
[https://nodered.org/docs/user-guide/writing-functions](https://nodered.org/docs/user-guide/writing-functions)
Add lines in your function so you can check what is happening to different variables.
---
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [30 July 2019 22:14 UTC](https://discourse.nodered.org/t/display-string-output/13855/5 "2019-07-30T22:14:10Z")
Thanks,
I was able to fix it so that both the mic and the accelerometer is running. However, the mic says NaN
I think it is because the accelerometer variables are still looping through.
I may need to apply some filter. Could you provide some help so that I can get both the microphone level and the accelerometer to run?
currently, the mic has no function but the accelerometer does as printed above with minor changes.
Thanks
---
### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [30 July 2019 22:55 UTC](https://discourse.nodered.org/t/display-string-output/13855/7 "2019-07-30T22:55:50Z")
we do not mind helping - but you need to contribute - paste up what you have that is working and the expected output and then show where you are stuck
Craig
---
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [31 July 2019 05:07 UTC](https://discourse.nodered.org/t/display-string-output/13855/8 "2019-07-31T05:07:05Z")
Ok, no problem. Here is my current code
```auto
var A_x = msg.payload.d.X;
var A_y = msg.payload.d.Y;
var A_z = msg.payload.d.Z;
var A_r = Math.sqrt(A_x*A_x + A_y*A_y + A_z*A_z);
var A_r_prev = context.get("A_r_prev") || 0;
context.set("A_r_prev", A_r);
msg.payload = ""+ Math.abs(A_r - A_r_prev);
// if ((A_r - A_r_prev) > 1000) {
// msg.payload = "Passed";
// }
// else {
// msg.payload = "Not Passed";
// }
return msg;
```
This is my state machine that I would like to implement in node red -- it has been coded in C and I do not know how to convert it to javascript and implement it into a function. Please let me know if you can provide any help!
```auto
if (*state == 0) {
if (abs(glob_prev_r - r) > 2000 && (msTick - *msTickStateChange > keeptime)) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tFirst Movement Detected!\t\t\r\n"
);
*state = 1;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
}
else if (*state == 1) {
if (abs(glob_prev_r - r) > 2000 && (msTick - *msTickStateChange > keeptime)) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tSecond Movement Detected!!!\t\t\r\n"
);
*state = 2;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
if (msTick-*msTickStateChange > resettime) {
sprintf(dataOut, "\n\n\r\t\tFalse Alarm\t\t\r\n"
);
//BSP_LED_On(LED1);
*state = 0;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
}
else if ((*state == 2) && (msTick - *msTickStateChange > keeptime)) {
if(msTick-*msTickStateChange > resettime) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tFalse Alarm\t\t\r\n");
*state = 1;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
else if (abs(glob_prev_r - r) > 2000 && (msTick - *msTickStateChange > keeptime)) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tSTEALING STEALING STEALING\t\t\r\n");
*state = 3;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
}
else if ((*state == 3) && (msTick - *msTickStateChange > keeptime)) {
if(msTick-*msTickStateChange > resettime) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tFalse Alarm\t\t\r\n");
*state = 2;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
else if (abs(glob_prev_r - r) > 2000 && (msTick - *msTickStateChange > fasttime)) {
*msTickStateChange = msTick;
sprintf(dataOut, "\n\n\r\t\tSTEALING STEALING STEALING\t\t\r\n");
*state = 3;
CDC_Fill_Buffer((uint8_t *) dataOut, strlen(dataOut));
}
}
glob_prev_r = (int) r;
}
Thanks
```
---
### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [31 July 2019 06:37 UTC](https://discourse.nodered.org/t/display-string-output/13855/9 "2019-07-31T06:37:17Z")
have a look at this FSM node - the author is a regular in here and is very helpful - he has coded heaps of examples also
> **[node-red-contrib-dsm](https://flows.nodered.org/node/node-red-contrib-dsm)**
>
> A dynamic state machine node based on the finite state machine model.
craig
---
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [31 July 2019 06:54 UTC](https://discourse.nodered.org/t/display-string-output/13855/10 "2019-07-31T06:54:17Z")
Thank you, I have read that information and it is very helpful.
One quick question. I am trying to modify the microphone output ( ST imported) in decibels.
With the acceleration, I called x, y, and z using var A\_x = msg.payload.d.X etc.
How do I modify/create a variable for microphone decibels?
this is the current code for the microphone
```auto
return msg;
```
all it does is return the decibels; I will need to create thresholds for the values but I need to find out how to create a variable equal to the decibel output
Thanks
---
### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [31 July 2019 07:46 UTC](https://discourse.nodered.org/t/display-string-output/13855/11 "2019-07-31T07:46:29Z")
> [@pinkdolphins](#):
>
> How do I modify/create a variable for microphone decibels?
Hve a look at this guide from the docs. It explains how to access the different parts of a message.
[https://nodered.org/docs/user-guide/messages](https://nodered.org/docs/user-guide/messages)
---
### Author:  [@ukmoose](https://discourse.nodered.org/u/ukmoose)
#### Post date: [31 July 2019 07:49 UTC](https://discourse.nodered.org/t/display-string-output/13855/12 "2019-07-31T07:49:55Z")
> [@pinkdolphins](#):
>
> this is the current code for the microphone
>
> ```auto
> return msg;
>
> ```
>
> all it does is return the decibels;
That will return the msg object that can contain whatever you want. If objects are new to you taking time to read an online javascript guide on objects and arrays is time well spent as you have already discovered they are fundamental in Node-RED. The w3schools javascript object and arrays guide is often recommended, easily findable with google
---
### Author:  [@pinkdolphins](https://discourse.nodered.org/u/pinkdolphins)
#### Post date: [31 July 2019 21:07 UTC](https://discourse.nodered.org/t/display-string-output/13855/13 "2019-07-31T21:07:57Z")
Thank you, one more question
I am trying to implement this state machine:
> **[node-red-contrib-state-machine](https://flows.nodered.org/node/node-red-contrib-state-machine)**
>
> A Node Red node for implementing a finite state machine.
Can you please explain how I can do that?
Thanks
---
### Author:  [@craigcurtin](https://discourse.nodered.org/u/craigcurtin)
#### Post date: [6 August 2019 04:02 UTC](https://discourse.nodered.org/t/display-string-output/13855/14 "2019-08-06T04:02:08Z")
The author of that State Machine is occasionally on here - but i note the project has not been particularly active lately.
I would suggest you would be better off with this one as the author has provided many documented examples and is also quite often on the forums here
> **[node-red-contrib-dsm](https://flows.nodered.org/node/node-red-contrib-dsm)**
>
> A dynamic state machine node based on the finite state machine model.
Craig