Sorry if this seems like going in circles, but have you tried different combinations of “privat publish”, “public publish”, “subscribe all” and “subscribe MY_DEVICES”?
Which do work, which not?
Have you removed all (forgive the expression) “obscure” code from the event handler down to the absolute minimum (e.g. set a var that gets published in loop independently)?
Can you setup your Cores with some minimal publish/subscribe only firmware, to find out if it’s your project code or your Cores/account/…?
I’ve tried public / public -> works, public / private -> does not work, private / private -> does not work.
I’ve tried a very simple sketch which does nothing but light up the LED at D7 - but it does not work. On all three cores - only public / public seems to work.
The command “spark list” lists all devices correctly …
Sorry for my impertinence, but could you also try private publish -> subscribe all? Just to have it all tested 
And could you also check if your Spark.subscribe() returns true to indicate a successful hooking up?
Nothing to be sorry about
Spark.subscribe() returns true in all cases - private publish / subscribe without filter doesn’t work either … 
I’m not sure if this applies to your problem, too.
But I have filed an “publish/subscribe” issue.
I stumbled about the same issue when trying the different scenarios-
Needless to say I never got private publish / private subscribe to work on any core but trying to subscribe to the same event, on the same core publishing the event, does not seem to work too.
In general, I realized that a lot of events published actually never call any action on the subscribing core (public publishing / public subscribing) - they work like 75% and the rest is kind of dropped.
I can see them on the api.spark.io website but different functions on different cores won’t be called - tried it with different cores, different events, different payload - it’s just not very reliable 
I’m not publishing too many events or such (during my test I was sending like 3 events a minute) - nor are my cores busy with other things.
I might just leave it there - I was kind of hoping to build a publish/subscribe mesh of some kind between my cores and I really like the cloud idea but is has to work like every time
Are you sure your code is correct? I don’t think the overloads are right.
I think here:
Spark.publish("color_values",pubstring,PRIVATE);
You are actually doing
Spark.publish(const char *eventName, const char *data, int ttl);
Passing in the PRIVATE as the TTL (which doesnt do anything because TTL is not impelmented, according to the docs).
I just tested your code and it works. But as soon as you do:
Spark.publish(“color_values”,pubstring, 60, PRIVATE);
The events dont get published to another Core. The Spark-CLI works fine receiving the events.
I might be incorrect here.
@Carsten4207, GOOD CATCH!
I have read that bit over and over, but it never popped into my eye.
@McTristan, maybe this helps. Since PRIVATE as TTL would cause the event to vanish after one second, this might have contributed to your problems.
There might have been a warning according type safety, but we never looked 
Try, as @Carsten4207 suggested
Spark.publish("pubdata", pubstring, 60, PRIVATE);
instead
Edit: Sorry, as I went back to the top of this thread I saw that you've already used the correct overload anyway
Yeah what I was pointing out was that if you pass in PRIVATE correctly it doesn’t work.
Hey All,
This has been bugging me too! So I pushed a fix for it today, Sorry about the delay! I think if you try private subscribe, it should now work as expected. 
Thanks,
David
Hey Dave,
seems to work now - great!!!
Thanks,
Sandro
P.S: I’ve also contributed some libraries to the Web IDE - the wtv020sd16p and the Keypad library
Awesome, thanks!
After testing it for a long while it seems, the cores which are subscribed to an event lose the subscription/connection after a while (usually hours - sometimes about half an hour). So it is (unfortunately) still not very reliable - it does, however, at least not matter whether the event is privately or publicly pushed
I know you guys can fix it - heck I’ve even (pre)ordered a couple of photon cores because I believe in you
It could be because the cloud connection was momentarily dropped and reconnected, since the subscription is lost if the cloud connection goes down. There’s a pending issue to fix this.
That would explain it, yes. Would be great if there would be a fix… I’m full of ideas and with 6 cores soon the fun really begins
Hey I am also having this issues It used to work but now it doesn’t is it because of the NOTE: A Core can register up to 4 event handlers. This means you can call Spark.subscribe() a maximum of 4 times; after that it will return false.
Any help is appreciated thanks in advance
Here is my code for the first core
#include "application.h"
#define zPin A2
#define Dpin D1 // Input pin for the led to blink when its moved
//Minium and Maxium data for the Z axes- the accerelometer
int zAccMin = 1722;
int zAccMax = 2400;
int sendLedPin = D1; // blinks when accelerometer is touched
int zAccPin = zPin; // Value for reading the data for the Z axe
int receiveLedPin = D2; //The pin that blinks when it recives.(Core-2 dependent LED)
int sendLedVal = 0; //variable for keeping the state
void ledTwoToggle(const char *event, const char *onOff);
void setup()
{
Serial.begin(9600); // sets the serial port to 9600
pinMode(zAccPin, INPUT);
pinMode(receiveLedPin, OUTPUT);
//digitalWrite(receiveLedPin, HIGH);//Ensure the local LED is set to off to begin with
pinMode(sendLedPin, OUTPUT);
Spark.publish("motionDetected1", "State", 0, PRIVATE);
Spark.subscribe("motionDetected2", ledTwoToggle, MY_DEVICES); // Set up Spark.subscribe();
}
void loop()
{
zAccPin = analogRead(zPin); // read the value of the Z axe sensor
if(zAccPin == (zAccMin) || zAccPin < (zAccMax)){
sendLedVal = !sendLedVal;
digitalWrite(sendLedPin, sendLedVal ? HIGH : LOW); //write the appropriate HIGH/LOW to the sendLed pin to turn it ON/OFF
//Serial.println("RED IS ON"); //Debugging
Spark.publish("motionDetected1", sendLedVal ? "ON" : "OFF"); //Publish the state to the Spark Cloud as ON/OFF
delay(250); // Primitive debouncing
}
}
void ledTwoToggle(const char *event, const char *onOff){ //Handler function for Spark.subscribe ()
Serial.println("onOffValue:");
Serial.println(onOff);
if (strcmp(onOff, "ON") ==0) //if sendLed on Core2 is ON
{
digitalWrite(receiveLedPin, HIGH);
} else if (strcmp(onOff, "OFF") ==0)
digitalWrite(receiveLedPin, LOW);
}
}
The code for core 2 looks like
#include "application.h"
#define zPin A2
#define Dpin D1 // Input pin for the led to blink when its moved
//Minium and Maxium data for the Z axes- the accerelometer
int zAccMin = 1722;
int zAccMax = 2400;
int sendLedPin = D1; // blinks when accelerometer is touched
int zAccPin = zPin; // Value for reading the data for the Z axe
int receiveLedPin = D2; //The pin that blinks when it recives.(Core-1 dependent LED)
int sendLedVal = 0; //variable for keeping the state
void ledTwoToggle(const char *event, const char *onOff);
void setup()
{
Serial.begin(9600); // sets the serial port to 9600
pinMode(zAccPin, INPUT);
pinMode(receiveLedPin, OUTPUT);
//digitalWrite(receiveLedPin, HIGH);//Ensure the local LED is set to off to begin with
pinMode(sendLedPin, OUTPUT);
Spark.publish("motionDetected2", "State", 0, PRIVATE);
Spark.subscribe("motionDetected1", ledTwoToggle, MY_DEVICES); // Set up Spark.subscribe();
}
void loop()
{
zAccPin = analogRead(zPin); // read the value of the Z axe sensor
if(zAccPin == (zAccMin) || zAccPin < (zAccMax)){
sendLedVal = !sendLedVal;
digitalWrite(sendLedPin, sendLedVal ? HIGH : LOW); //write the appropriate HIGH/LOW to the sendLed pin to turn it ON/OFF
//Serial.println(WHITE IS ON"); //Debugging
Spark.publish("motionDetected2", sendLedVal ? "ON" : "OFF"); //Publish the state to the Spark Cloud as ON/OFF
delay(250); // Primitive debouncing
}
}
void ledTwoToggle(const char *event, const char *onOff){ //Handler function for Spark.subscribe ()
Serial.println("onOffValue:");
Serial.println(onOff);
if (strcmp(onOff, "ON") ==0) //if sendLed on Core1 is ON
{
digitalWrite(receiveLedPin, HIGH);
} else if (strcmp(onOff, "OFF") ==0)
digitalWrite(receiveLedPin, LOW);
}
}I know this has been a while. But has the dropout issue been resolved?
This weekend I made one Spark Core listen to some events from another Core, and after a while (not sure duration) the listening Core doesnt receive the events anymore.
Any updates?
@Dave - any updates to this? Surely this is a really huge bug to squash? Or am I missing something? Doesn’t this bug’s existence cripple the whole spark subscribe/publish thing? I am trying to have a mini network of four particle cores talking to each other on a WiFi network and it’s just not going to work if a bit of network disruption causes them to ignore each other? Or is there another way to do it?
It took me a while to find the issue on github, sorry. It looks like this have been fixed in the HAL branch that is on Photon and is coming soon to Core: