How common is it to have a separate micro to handle comms in SCADA sensors?

[e100]

I'm wrestling with the problem of a slave microcontroller that needs to be constantly listening for messages from a master, but also needs to be able to do other time-critical things that requires interrupts to be temporarily disabled. My choices are either to write 'retry' code to deal with occasional (1 in 200) comms failures, or else use a dedicated micro to handle the comms. Neither seems like an elegant solution.

Mike

[ebclr]

One possible solution that will require open mind

https://www.xmos.com/support/boards?product=17441

[gmb42]

Speaking as a developer on the master side, some of the RTU\PLC's I've used in the past have had a separate communications processor, but newer devices seem to have enough horsepower to not need that.

Master side software is well versed in handling comms errors to slaves, both transmission medium (i.e. radio) and slave  related and dropping 1 in 200 messages won't be a worry as long as no data is lost by the slave after the retry succeeds.

What protocol are you using?

[e100]

Speaking as a developer on the master side, some of the RTU\PLC's I've used in the past have had a separate communications processor, but newer devices seem to have enough horsepower to not need that.

Master side software is well versed in handling comms errors to slaves, both transmission medium (i.e. radio) and slave  related and dropping 1 in 200 messages won't be a worry as long as no data is lost by the slave after the retry succeeds.

What protocol are you using?

It's just a serialized struct passing over a half duplex rs485 connection. Master sends a message, slave responds with measurement data.

[Rerouter]

depending on your main hardware, see if your hardware has a dedicated buffer for the serial I/O, if so it would greatly increase the amount of blind time you can deal with, unless your running your micro very slow or your serial very fast, you should be able to come back and read in or prepare the output buffer and let the hardware do the heavy lifting,