Data retention during/after Power shutdown

T3000 Software
1

This is a follow-up from side-comments on “Power Cycle” in a topic in Sept 2024. The standard documentation does not cover this.

Please clarify what happens to the T3-xB series during/after a power failure.

  • Digital Outputs revert to their unpowered state?
  • ANALOG outputs go to zero?
  • Variables - current value is lost?

The earlier post suggested COUNTERS are auto-backed up every few minutes. There is no specific “class” for counters - what is included in this??

  • INPUT counter ie ranges 45 or 55?
  • VARIABLES with ranges relating to a countable-quantity eg, 40-kWh, 46, 47, 48, 49 sec, mins, hours, days, 55-COUNTS, 75-kg, 60, 61, 62 GAL CF, BTU.
  • What about VARIABLES with custom range? eg litres, cubic meters etc?

What happens on power restoration??
Do outputs or variables restore to their pre-outage condition?

In my application I need to achieve orderly shutdown of external devices on power failure and orderly-restart on resumption of supply. No equipment can/will run during any power outage. I do want to retain certain status points and accumulated data across any power outage. Basically I intend to put all outputs to “OFF” state upon power-off and, after power returns, to re-start all the equipment via normal logic. I do not plan to “resume just where you left off”.

I am including a UPS power supply (able to run controller for >1hour) and No-volt detection so will have the ability to detect power-loss and “save” data in some way. Is an SD card a useful option here? (Previous posts mention there is no program function/instructions for saving to SDcard.)

Also, what happens during the controller restart boot sequence? I presume program scan is suspended? Are inputs and outputs (and variables) frozen during boot-up? Can I find/create some logic input that indicates “controller now ready for action” and use this to control restart?

2

On loss of power the outputs go off. As soon as power is restored they will go on or off according to your program. It takes a few seconds for the bootup and after that the scanning will begin and outputs will start controller per your sequence.

The inputs will get stored to flash periodically, if you are counting pulses on one of the inputs you will lose at most a few minutes of data. The interval is on the order of a few minutes, its not exposed as a setting that you can adjust in order to protect the on board flash from repeated writes.

The vars are not stored to flash, they will revert to whatever they were when you loaded the prog file.

There’s no special commands or features to control the sequence of events after a power up but you could implement something in control basic. Set a variable flag to 0 and save it to the controller by loading the *.prog file. On power up you read that flag and if its zero do your startup procedure. Then set the flag to ‘1’ to signal the system is done with the power up routine.

All the best with your programs, sounds pretty sophisticated.