💬 Temperature Sensor

[ben999]

@mfalkvidd thanks a lot. Yes, that looks good to me. I will have a go.

The real big question now is about what happens when one or more sensor fails on the line.
I am not talking about removing a sensor, which doesn't produce any fault.
My concern is how does a DS18 ends its life under normal operation? Complete shortcut?

[mfalkvidd]

@ben999 I don't think there are any guarantees on how it will fail. If there are, the datasheet should list them.

[zboblamont]

@ben999 I cannot remember WHERE I read it, but if a DS18B20 fails it will either send impossible results when addressed or fail to be addressed at all as it is digitally addressed. Only cable short circuits can pull the entire chain down, as I found out when two socket pins had crossed over (sensor crimped into telephone plugs).

[ben999]

@mfalkvidd thank you for the idea. Had a look (boooooring reading for me :D ) but no mention to failiure

@zboblamont you're right. Seems that a faulty sensor return "85" (top of my head). And a "dead" sensor looses its bus address (next sensor on the chain takes its address and so on)

Thanks a lot gentlemen :)

[rejoe2]

@ben999 said in 💬 Temperature Sensor:

And a "dead" sensor looses its bus address (next sensor on the chain takes its address and so on)

That's not exactly right. Each of the 1-wire devices uses a hardcoded, unique address that can not be changed.
So if you use the standard sketch with multiple DS18B20, in case of detached or replaced sensors you may get reported the measured temperatures comming from the same physical DS18B20 device under a different ChildID (after node reboot). To avoid effects like that, one has to take additional measures as described here . In short:

• Use an array with the physical ID's to address them
• Store a hash-array (done automatically) to identify "known" physical ID's that have once been attached to the bus as well as the ChildID used for MySensors.

[ben999]

@rejoe2 oooooooooh great! thanks a lot, exactly what i was looking for !!!

[rejoe2]

@ben999 You are welcome :grinning:

[pintman]

When I try to compile the sketch for an ESP8266 I get an error in DallasTemperature.h which results in an error in OneWire.h

OneWire.h:108:2: error: #error "Please define I/O register types here"  #error "Please define I/O register types here"

Is it possible to make the sensor run on an ESP?

[cashew75]

Hi, I'm having a hard time getting this Temperatursensor to work with Home Assistant. When i start it it doesn't register with the HA. If I use the same hardware and switch out the sensor to a DHT sensor (new sketch of course) then it works out of the box, HA sees the sensor. I've tried changing the Dallas DS18B20, but nothing. If i look at the logs the gateway have no problem with the sensor. Is there something in the code for the sensor that doesn't add up to it being presented to HA in the right way? I'm quite the newbie when it comes to programming.

[gohan]

Have you tried another controller like mycontroller?

[cashew75]

@gohan No I have not. I have a RF-Link also connected to the HA and it's working great. As I said, if I use the same hardware that I used to control the Dallas sensor and change the sensor to a DHT sensor the DHT sensor is accepted by HA and shows up as a sensor. That's why I was asking if there is something in the code for the Temperature sensor sketch that has to be changed to be able to present it to HA.

[gohan]

pls post the code that is not working

[cashew75]

@gohan Thanks for the quick reply! Well I've use the standard sketch for this Temperatur sensor. This is the code i've got.

// Enable debug prints to serial monitor
//#define MY_DEBUG 

// Enable and select radio type attached
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69

#include <SPI.h>
#include <MySensors.h>  
#include <DallasTemperature.h>
#include <OneWire.h>

#define COMPARE_TEMP 1 // Send temperature only if changed? 1 = Yes 0 = No

#define ONE_WIRE_BUS 3 // Pin where dallase sensor is connected 
#define MAX_ATTACHED_DS18B20 16
unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)
OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
DallasTemperature sensors(&oneWire); // Pass the oneWire reference to Dallas Temperature. 
float lastTemperature[MAX_ATTACHED_DS18B20];
int numSensors=0;
bool receivedConfig = false;
bool metric = true;
// Initialize temperature message
MyMessage msg(0,V_TEMP);

void before()
{
  // Startup up the OneWire library
  sensors.begin();
}

void setup()  
{ 
  // requestTemperatures() will not block current thread
  sensors.setWaitForConversion(false);
}

void presentation() {
  // Send the sketch version information to the gateway and Controller
  sendSketchInfo("Temperature Sensor", "1.1");

  // Fetch the number of attached temperature sensors  
  numSensors = sensors.getDeviceCount();

  // Present all sensors to controller
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
     present(i, S_TEMP);
  }
}

void loop()     
{     
  // Fetch temperatures from Dallas sensors
  sensors.requestTemperatures();

  // query conversion time and sleep until conversion completed
  int16_t conversionTime = sensors.millisToWaitForConversion(sensors.getResolution());
  // sleep() call can be replaced by wait() call if node need to process incoming messages (or if node is repeater)
  sleep(conversionTime);

  // Read temperatures and send them to controller 
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {

    // Fetch and round temperature to one decimal
    float temperature = static_cast<float>(static_cast<int>((getControllerConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;

    // Only send data if temperature has changed and no error
    #if COMPARE_TEMP == 1
    if (lastTemperature[i] != temperature && temperature != -127.00 && temperature != 85.00) {
    #else
    if (temperature != -127.00 && temperature != 85.00) {
    #endif

      // Send in the new temperature
      send(msg.setSensor(i).set(temperature,1));
      // Save new temperatures for next compare
      lastTemperature[i]=temperature;
    }
  }
  sleep(SLEEP_TIME);
}```

[pepson]

Anybody has sketch for sensors dallas DS18b20 with identify it with ID Dallas ?
And i can change value 16 to more sensors ? Example 20 ?

[APL2017]

Looking at code example it seems to be sufficient to set bool metric = false to get readings in Fahrenheit, but node still returns readings in C. Any idea why?

[mfalkvidd]

@apl2017 if I'm looking at the same sketch as you are looking at, the metric variable is never used. getControllerConfig() is used to fetch the controller's metric setting instead.

[gniazdoj]

@Rene046
Hi guys

Hi
can you advice how to manage Domoticz to display 2 decimals under Temperature sensors page, when following line MsgTemp.set(temperature,2) I can see on arduino serial monitor, mysensors sent 20.75 value, the same value i can see under child item with Hardware tab but not on sensor where 20.75*C is rounded to 20.8. its fine for general log but i want to have stable temperature for heating system. I have added code to count average from last X records like 20 or 40 with 0.25 steps, this stabilize Heating system and protect it against on/off to frequently.
Additionally when i use JSON it will present proper value under sensor page, same with ESPEasy and 2 decimal configuration on ESP.
do you know how i can changed domoticz to force him to present 2 decimals?

Mysensors 2.3.1/2.3.2
Domoticz 4.10717
raspberry pi

Thank you
Jakub

[kimot]

Domoticz globally or only with MySensors ?
My Domoticz is the same version like yours.
Temperatures from ESPeasy are with two decimals on Temperature sensors page, but on devices page only one decimal.
Exactly the opposite like you wrote.

[gniazdoj]

@kimot
Hi
Thank you for feedback.
I have this issue only with mysensors. it's exactly like you wrote. Hardware tab, present 2 decimals ( for mysensors and espeasy). Device tab, present 1 decimal ( for all sensors), Temperature tab shows 2 decimal for esp easy and JSON updates but 1 decimal for mysensor. Not sure why.

Temporary I managed to workaround by using script taking data from Hardware page - child and sending JSON update all started by crone updating dummy sensor.

like this:

TEMP=`curl -s "http://X.X.X.X:XX/json.htm?type=command&param=mysensorsgetchilds&idx=40&nodeid=0"| awk 'NR>1{print $5}'| sed 's/"//g;s/^.//;s/)//g; s/,//g;/^$/d;s/]//g;' | sed -n '3,2p'`
IDX=255
curl -s "http://X.X.X.X:XX/json.htm?type=command&param=udevice&idx=$IDX&nvalue=0&svalue=$TEMP"

but for sure this can be workaround by dzVents and JSON handling results but i'm not skilled enough for that :)

Thank you
Jakub

[garubi]

The note before the example sketch states that you should use the "modified" library from MySensors examples.
But as of today, with MySensors 2.3.2 and Arduino 1.8.15 I used the standard DallasTemperature library (provided by the Arduino's Libraries manger) with no problems at all.

Using the "standard" Arduino libraries is a grate advantage, so I the custom library is no more used, it could be useful to update the guidelines in the page.

Stefano