Watchdog for each metric

Ignition Modules
1

Hi all,
is there a way to add a watchdog (number counting up for each new value for individual metric) to each metric in SparkPlug B (Transmission Module).
We require something to be sure, that we don’t miss any data.

Thank you,
André

2

This is not a feature of Sparkplug. However, you could potentially implement something yourself by using a more complex datatype (like a Template). But, Sparkplug has built in mechanisms to ensure there is no data loss. This webinar from a while back explains in detail: https://www.youtube.com/watch?v=3syYeTg6RBc

3

HI @wes.johnson,

thank you for your response. So there is no way to monitor data integrity with OOB functionalities of SparkPlugB (Transmisison Module) without writing our own code.

Thank you,
André

4

Sparkplug itself and the architecture ensure data integrity. If a message is missed, that will be handled by the modules via Sparkplug mechanisms and result in a rebirth request to renew the session.

5

Understood, but there is no way for a end-user to verify the data integrity or how does Sparplug itself check the integrity of a message?

  1. There is seq. number for each message
  2. A seq. number for metric is not available
  3. A checksum for the whole message is not available
6

All of those statements are true. But keep in mind MQTT sits on top of TCP/IP which does have a checksum. Also as I mentioned, a seq number could be added to each metric via a template.

7

Thank you Wes :slight_smile:

Can you give me a hint where I can find how templates can be created in the Ignition Transmission Module? Should this be done via UDTs or is there another mechanism?

8

Yes - UDTs in Ignition get converted to Sparkplug Templates via Transmission. See here for a starting point: User Defined Types (UDTs) within Transmission - MQTT Modules for Ignition 8.x - Confluence