What speed can I expect to sync a note?

Troubleshooting
1

Hi!
I am excited to experiment with Blues devices for a couple of projects I am working on. Here’s a question that I could find documented anywhere: When using a cellular Notecard, how long should I expect Note sync’s to take? What can be done to optimize for sync speed? I have an application where I will be remote switching a device. The device needs to respond/switch within a few seconds of a command being sent. Is this feasible with the Blues technology?
Thanks

Edit 1: I am currently using the NOTE-NBGL-500 — LTE Cat-M-Global.

2

Hi,

Welcome to the forum. A great thing about the Blues ecosystem is that you can configure the Notecard to minimize latency by stay connected to Notehub.io and to sync immediately when a note is created or a signal is sent. Thus, when a note is added on either side (cloud or device) it will be sent immediately. I regularly see notes sync sent from notehub to notecard in about a second. Signals are only for cloud to device messages.

Gracefully, when using notes, if a connection is temporarily unavailable (for example driving through a tunnel, or if the battery is dead on your device) notes will be queued and sent when a connection becomes available. Imagine it like email or TCP with long timeouts appropriate for IoT.

Conversely, you use signals, and think of it like UDP because it will only send a message to a device that is currently connected to the network and Notehub. Messages sent to offline devices will be dropped, which might be what you want if for example you’re unlocking a gate and don’t want it to unlock at some random time after an interruption to the cell network.

Welcome to the forum and please keep the good questions coming.

-Carl

3

Hi Carl and thanks for the warm welcome!
I read through the latency article and this is indeed exactly what I was looking for. I’m thinking that using signals will work well in my application. Regardless of note or signal selection, it sounds like I will want to have "mode": "continuous" and "sync": true. Do these settings imply that the modem will stay on at all times? Do you know the approximate current draw associated with these settings? In addition to low latency, my project will also be battery powered so energy conservation is important… I realize that I will need to choose a balance between latency and battery life.

4

Yes, I usually use { "req": "hub.set", "mode": "continuous", "sync": true, "inbound": 1} when I want to just put my notecard into the fastest (most power-hungry) mode. Yes, the modem will stay powered on and connected to notehub to avoid the handful of seconds (or more) it can take to find a cell tower and get a secure connection to the notehub cloud.

When using notes to send time-sensitive messages back up to the cloud, you’ll want to set "sync":true on the note.add request like this {"req":"note.add","sync":true,"body":{"foo":"bar"}}.

The general power-draw info for the NOTE-NBGL-500 is here on the datasheet. To be more precise, you’ll want to do your own measurements when you get your whole device put together. The NOTE-NBGL-500 does support GSM, so you’ll want to be prepared for short spikes of 2A if there is GSM (2G) coverage you’re going to be depending on.

If four hours of continuous operation is sufficient between charging opportunities, you might be well served by the $10 Scoop hybrid supercapacity which charges really fast, and doesn’t have li-ion shipping restrictions.

By the way, I would be remiss not to mention that latency in the world of wireless communication depends on so many factors, we can’t guarantee anything. I’m just saying I’ve seen it regularly working faster than a second or two.

Because network latency is dependent on RAT (e.g. NB-IoT, GSM, Cat-M, Cat-1), device signal strength, and the state of the Notecard’s connection to Notehub, Blues does not estimate nor document expected latency thresholds for the Notecard. faq

You can check what which RAT (radio access technology, like GSM) your devices have been using:

  1. Notehub.io > your project >
  2. Devices page > Sessions button > Download button
  3. Search the json file for "rat":"gsm"