Possible to check if ThingSpeak is ready to receive data?

I'm thinking about adding a second channel, but I'd like both to receive data as often as I'm allowed to send it. I'm worried that if I program both devices to send data every 15 seconds, only one channel will receive data while the other will keep trying while the site is unavailable. I'm wondering if there's a way to check whether or not ThingSpeak is ready to receive data so that I can program my timers to start after receiving that confirmation. Thanks!

[Ameer Hamza]

Why will the site be unavailable? Have you tried sending data to both channels?

[BRIAN MINOR]

I had a while back, but it was while I was still learning and experimenting with that process. I may not have had one of the units programmed correctly. I know I'm only able to send data every 15 seconds. The way the data was received, I assumed that limit was across all channels, not 15 seconds per channel.

Answer 1

[Ameer Hamza]

According to the answer here: https://community.thingspeak.com/forum/thingspeak-api/rate-limit-on-read-operations/ the limit is imposed per channel for free accounts.

[Christopher Stapels]

ThingSpeak is always ready to recieve data as long as you havent sent data to that channel withinn the time window defined by your license type (15 seconds for free, 1 second for paid). Just as Ameer says, the limit is per channel, so you can send data to two different channels simultaneously with two different devices.

[BRIAN MINOR]

I guess I'm looking for error handling techniques. I'm new to this and I've been working from an online example using a ThingSpeak library on Arduino. I know that if I manually enter something like "https://api.thingspeak.com/update.json?api_key=xxxxxxxxxxxxx&field1=111&field2=4.98&field3=77.20" into a browser I can tell from the response whether or not data was received. It would be nice to incorporate that feedback.

One of my fields contains an instance counter that increases every time I try to send data. Even though I'm waiting more than 15 seconds to send data each time, one out of every few instances doesn't get recorded.

[Ameer Hamza]

You can use try-catch block to handle the errors. For example

try
    response = thingSpeakWrite(id, val, 'WriteKey', '#####')
catch ME
    disp(ME.message)
    disp('Data couldn''t be written to the channel.')
end

If the data is sent faster then the allowed limit, it will not throw an error. It will just print the message.

[Ameer Hamza]

If you are using webread(), then you can check from the response. If it is '0', then the data was not written to the channel.

[BRIAN MINOR]

Thanks! Before your response I found this. Would your example give the same range of responses? I'm printing the response to Serial and it prints within milliseconds of sending the data to ThingSpeak when it posts correctly. Every few instances when I send the data I get a response of -301 and when that happens there is a 10 second delay between sending the data and printing to Serial.

Here's the important part from the link:

int writeTDData(long TSChannel,unsigned int TSField1,float data1,unsigned int TSField2,data2,char* ReadAPIKey){
  ThingSpeak.setField(TSField1,data1);
  ThingSpeak.setField(TSField1,data2);
   
  writeSuccess = ThingSpeak.writeFields(TSChannel, writeAPIKey);
  return writeSuccess

Edit: I should be clear that when I get the -301 error the data wasn't posting. I've added a while loop that resends the data when encountering this. So far it always sends immediately on the second attempt. I see I would get a -401 response if I try sending data faster than every 15 seconds and the response is 200 when data posts correctly.