EtherCAT Arduino Accelerometer project questions

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1

Hi,

I am thinking about switching my data collection system from a Raspberry Pi-WIFI based solution to an Arduino-EtherCAT solution.

The current set up is, 4 DAQ nodes each of which is collecting data (~1KHz sample rate) from ADXL 355 accelerometers. Each DAQ node is a Raspberry Pi 3 that broadcasts acquired data via MQTT to a central database. Synchronized data collection has proven difficult to maintain in this system. Whilst triggering acquisition is fine each node appears to have its own idiosyncrasies that throws the sampling out of phase.

Whilst looking for a solution I came across EtherCAT & then the EasyCAT shields for Unos.

I know its possible to connect ADXL 355 to an Arduino. What I'm not too sure about are the following,

  • Can I use the EtherCAT master to clock synchronize acquisition across multiple DAQ nodes at 1KHz?

  • Is an Uno capable of storing enough sample data between broadcast requests?

  • Given that both the EasyCAT sheild & the ADXL 355 make use of the SPI bus is this solution a non-starter anyway?

2

Can you draw a timing diagram showing how you want the system to behave?
In particular show the timing tolerances. See UML Timing Diagrams - Overview of Graphical Notation for an example.

It's unclear from the description if the system runs continuously or in a burst mode where you take a series of measurements, then at a later time send the data back.

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