I used an ICON switch for this test but it applies to other Insteon switches as well. If you press and immediately release the top of the paddle, an Insteon ON command (0x11) is issued. If you press and hold the top paddle the ICON switch sends a Start Manual Change command (0x17) that starts a bright sequence in the responder(s). When the top paddle is released the switch sends a Stop Manual Change command (0x18) which stops the bright level ramp up process in the responder. If you double tap the top paddle a Fast On command (0x12) is issued. SwitchLincs, KPLs, ToggleLincs, they all work the same way.
The Insteon command format for all of these commands is…..
From Insteon device address aa.aa.aa Insteon address of ICON switch
To Insteon device address bb.bb.bb Insteon address of the responder
Flags indicating type of command
Cmd1 field for example a 0x11 is an ON command
Cmd2 field is the Group number of the ICON switch paddle
Nothing regarding LD1/2/3 data stored in the responders link record flows over the powerline regardless of whether there is a link in one direction or the devices are cross-linked.
You are correct that you have to query the controller (ICON switch in this example) to know what the state of the controller is at the instant the query command is issued. If the result of pressing the ICON paddle is to turn On the ICON switch with a slow ramp rate, when you query the ICON switch you get back a bright level representing the ICON switch bright level at that instant. If you issue the query 5 seconds later you could well receive a different bright level as the device ramps up slowly to its ultimate bright level. If the ICON switch was ramping up at the default ramp rate the query is going to return the “local” bright level that has been configured for the ICON device.
This is the way of Insteon. Nothing here is unique to EZSrve. There is an Insteon Details document on the Smartlabs web site that covers all of this and much more. This document is years old but the basic insteon information, command formats, link record formats, etc. has not changed.