I think of a multi output device like a Keypadlinc. If you want to control 8 button LEDs of a KPL, you need 8 links. Each link to the KPL would use the same device address but would have a different group number. For a KPL the group number follows the button number.
Using KPL1 as the Controller and KPL2 as a Responder…
KPL1 Button A Controller of KPL2 Grp 1 … KPL2 Responder to KPL1 Grp1 Button C
KPL1 Button B Controller of KPL2 Grp 2 … KPL2 Responder to KPL1 Grp2 Button E
KPL1 Button C Controller of KPL2 Grp 3 … KPL2 Responder to KPL1 Grp3 Button F
And while I was doing the above chart I see your question. With the PLC as KPL1 and EZFlora as KPL2, how do you get the PLC to use incremental Group numbers when all you have is the Set button to put it into controller mode. The EZFlora is programmed to select which button (zone) by the number of Set button presses during the responder linking process. How do you do that with the PLC without the benefit of HA software. I don’t know the answer to that. HA software would write the PLC link records with whatever Group numbers it needed to establish multiple links to the same responder device. Just as KPL1 would have multiple “controller of” link records to KPL2, each with a unique Group number. Can’t change what happens on the responder end. The responder needs a unique Group number for each zone because the local data in the responder of link record identifies which zone (button if a KPL) is being controlled. I’ll look through the various Smarthome forums to see if the answer is documented there. Since SH has HouseLinc Desktop they may not have found it necessary to document the procedure, assuming one exists. Are you sure your HA software does not have the ability to establish link records in the PLC?
Just read your last post. Using a Keypadlinc as the controller for the zones of the EZFlora, by hardware/firmware design, each KPL button uses a unique Group number. Putting KPL button A into controller linking mode results in a “controller of” link record using Group 1 being written in the KPL once a responder sends it Insteon address back to the KPL. When doing the EZFlora side of the link, you would select which zone is being controlled by Button A (Group 1) by the number Set button presses. Then you would put KPL Button B into controller linking mode which results in another “controller of” link record in the KPL, with this link record using Group 2 (button B group number). When doing the EZFlora side of this link you would again select which zone is being controlled by the number of Set button presses. Linking 8 buttons on a KPL to the EZFlora would give you control over 8 zones.
As you noticed when putting both devices in the same room, when you first press the Set button on the EZFlora, the PLC is sent a message identifying the EZFlora and the link process is complete as far as the PLC is concerned (as it would be with something like a LampLinc). The extra process of pressing the EZFlora Set button to identify the zone is known only to EZFlora. The PLC knows which Group number it sent out when it identified itself as being in controller mode. That along with the Insteon address of EZFlora is all it needs. EZFlora stores that Group number in the responder of link record in EZFlora along with the zone number being controlled by that Group number in data byte 3. Just as a responder KPL would store the button number being controlled in the same data byte.
That still leaves the question of how to get the PLC to use unique Group numbers. KPL as a controller does it by design. Same thing with HA stuff. Just need to find out if/how that can be done with a stand alone PLC.