unsolicited messaging

Back in the 1990's I used unsolicited message to exchange data.

Aka, instead of the HMI polling the plc for data, I sent the data from the plc when it changed.

Why is this not a thing?

Is this even still possible?

And I could change the tv channel in a bar w/ my palm pilot.

And all vcrs worked the same.

I think it depends on the HMI.

Some HMIs do offer IO Messaging. I was just reading up on the Cmore from Automation Direct and setting it up to receive IO data from a ControlLogix processor, instead of asking for it.

Personally I could see the value of both, but the way HMIs are used in my applications (and, I would cautiously say, many applications) the need for the PLC to be the one sending the data rather than the HMI just asking for it doesn't really exist.

ganutenator said:

And I could change the tv channel in a bar w/ my palm pilot.

And all vcrs worked the same.

Click to expand...

As long as you had an infrared transmitter, knew the TV/VCR model and IR codes, you could. But not sure what that really has to do with HMI to PLC data transmission other than the very generic "data being sent".

ganutenator said:

And I could change the tv channel in a bar w/ my palm pilot.

Click to expand...

If you miss that a lot of phones have built in ir blasters