How place 15 Float values in one MQTT payload Pub sub Client

Projects Programming
1

I need to send 3 energy sensor readings with one single payload via MQTT.

So what I have done so far.

The 15 float values is in an array ph[0]- ph[14]

I then convert the values to String with dtostrf

   char  v1[10], c1[10], p1[10], e1[10], pf1[5];
   char  v2[10], c2[10], p2[10], e2[10], pf2[5];
   char  v3[10], c3[10], p3[10], e3[10], pf3[5];
   
// Phase 1
   dtostrf(ph[0],2,2,v1);
   dtostrf(ph[1],2,2,c1);
   dtostrf(ph[2],2,2,p1);
   dtostrf(ph[3],2,2,e1);
   dtostrf(ph[4],2,2,pf1);
// Phase 2
   dtostrf(ph[5],2,2,v2);
   dtostrf(ph[6],2,2,c2);
   dtostrf(ph[7],2,2,p2);
   dtostrf(ph[8],2,2,e2);
   dtostrf(ph[9],2,2,pf2);
// Phase 3
   dtostrf(ph[10],2,2,v3);
   dtostrf(ph[11],2,2,c3);
   dtostrf(ph[12],2,2,p3);
   dtostrf(ph[13],2,2,e3);
   dtostrf(ph[14],2,2,pf3);

Then create a comma separated payload with sprintf

      char data[160];
      sprintf(data, "%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s", v1, c1, p1, e1, pf1, v2, c2, p2, e2, pf2, v3, c3, p3, e3, pf3);
      mqtt.publish("energy/data", data);

It works for a couple of times and then the program crashes. Is there a better way of sending the info via MQTT , I have a limited amount of band width so I need to send the data with one payload.

2

could you be overrunning you data[] array?
try printing the value returned by sprintf() which is the number of characters written to the array (excluding null)
also consider using snprintf() when the array length is specified

3

What does crashes mean?

Limit the size of the float to 3 or 4 or 6 decimal points.

4

why do you convert it to String?
Send it as array of float.

5

I will need to have a look at the array of float.

I am also playing with the idea to convert the values to INT by multiplying with 100 (only need 2x decimals).
Should that also be a solution?

6

What happened when you tried?

7

So far the program seems to be running stable. But will run it for the day and see if it holds up.

8

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.