Explicit Address Command Response; Global Address Command Response; Unsolicited Message - Aprilaire 8800 Programmer's Manual

ExPlICIT ADDRESS COMMAND RESPONSE

Explicit Address Commands are commands sent by the Host controller to a single node at a specific address . Upon receipt of a completed Explicit
Address Command from the Host controller (including the <CR>), each node determines if it is the addressee of the command . If the node is not
the addressee of the command, the command is discarded . If the node is the addressee of the command, it interprets and executes the command
and then prepares a response for the Host controller (depending on the command response control setting C1 – C19) .
The command response (if required by the command response control setting) is transmitted by the node during the Solicited Response Sub-slot of
the slot . Since the communication timing and control variables are reset upon receipt of the <CR> from the Host controller, Slot 1 and the Solicited
Response Sub-slot are the currently active slot and sub-slot . As such, if the explicit address command was for node 1, the node may begin
transmitting the response immediately after the command is received . The entire response must be transmitted within the Solicited Response
Sub-slot of the slot . (Maximum bytes per response: 62 = 65ms * 10 / 9600 .)

glObAl ADDRESS COMMAND RESPONSE

Global Address Commands are commands sent by the Host controller to all thermostats . Upon receipt of a completed Global Address Command
from the Host controller (including the <CR>), each node determines that the command is a global command . Each node interprets and executes
the command and then prepares a response for the Host controller (depending on the command response control setting C1 – C19) .
The command response (if required by the command response control setting) is transmitted by the node during the Solicited Response Sub-slot
of Slot n, where n is the node address . Since the communication timing and control variables are reset upon receipt of the <CR> from the
Host controller, each node must wait for its respective slot before transmitting its response . The slot time from the reset caused by the <CR>
synchronization can be calculated using the following equation:
t = (n –1) x (slot width)
Where n is the node address and slot width is the duration of a slot based on the baud rate .
The node may begin transmitting the response once the communication timer matches the calculated time t, which corresponds to the start of
the Solicited Message Sub-slot of its respective slot . The entire response must be transmitted within the Solicited Response Sub-slot .
(Maximum bytes per response: 62 = 65ms * 10 / 9600 .)

UNSOlICITED MESSAgE

Unsolicited Messages are messages sent by the node to the Host controller when a Change-of-State (COS) is detected . Change of State
responses are sent by the node so that the Host controller need not poll each node to determine if any node control variable change has
occurred .
An Unsolicited Message is transmitted by the node during the Unsolicited Response Sub-slot of Slot n, where n is the node address . Slot timing
is synchronized upon a previous receipt of a <CR> . Each node must wait for its respective slot and sub-slot before transmitting its response . The
transmit time from the last synchronization or Communication Frame restart (start of Slot 1) can be calculated using the following equation:
t = (n –1) x (slot width) + (sub-slot width)
Where n is the node address and slot width and sub-slot width are the durations of a slot and sub-slot, respectively, based on the baud rate .
The node may begin transmitting the message once the communication timer matches the calculated time t, which corresponds to the start
of the Unsolicited Message Sub-slot of its respective slot . The entire response must be transmitted within the Unsolicited Response Sub-slot .
(Maximum bytes per response: 62 = 65ms * 10 / 9600 .)
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