Hi All,

I want to use a Logo! to control some relay's over Modbus-TCP, but with a failsafe.
Right now the controller sends either a on or off command every 5 seconds, even if there is no state change.
But i want the Logo! to switch off the relay if for example it didn't receive a ON command for 10 or 15 seconds.

My solution right now is to set a modbus coil and use that to drive the Logo! relay, but there is no failsafe in this. How do i achieve this?

Kind regards

Hi mate,

LOGO does not support failsafe protocol.

You can use MODBus TCP, no problem.

Hello AutoGen,

For this to work, the status of the relays must be available via Modbus-TCP.

Regards Ella_68

(Translated with google)

AutoGen_1856652

But i want the Logo! to switch off the relay if for example it didn't receive a ON command for 10 or 15 seconds.

Send  "heartbeat" pulses via modbus - change one (unconnected) coil state after every 5 seconds (coil ON, wait 5 seconds, coil OFF, wait 5 seconds, coil ON, wait 5 seconds etc). On LOGO you can connect this "hearbeat coil" NI (network input) to M flag for further processing and debugging.

Now, on LOGO you can make kind of watchdog with delayed ON/OFF triggers - if "heartbeat" pulses not received for more than 20 seconds (M flag stays steady), then switch your relay OFF.