OT, R
Outdoor temperature
COS: C3
Permissions: Read/Write
Query
Command
Syntax:
SN[#] OT?<CR>
SN[#] R?<CR>
Description: Requests the outdoor temperature sensor reading .
Assignment
Command
Syntax:
SN[#] OT=[value][scale]<CR>
Description: Sets the outdoor temperature to
[value]
. The alternate R version does not apply .
Examples:
SN1 OT=55F<CR>
SN OT=-10F<CR>
Response or
COS Message
Syntax:
SN[#] OT=[value][scale]<CR>
SN[#] R=[value][scale]<CR>
Description: Sets the outdoor temperature to
[value]
. The OT version is used for COS Messages and the alternate
R
version is only used for responses .
Example:
SN1 OT=-10F<CR>
Node address 1 responds with an outdoor temperature of -10°F .
Parameters
Range
value:
sensor value
Fahrenheit
[-40 – 130]
Celsius
[-40 – 55]
no sensor attached or error
[--]
scale:
temperature scale
[F, C]
F:
Fahrenheit
C:
Celsius
The source of the outdoor temperature value is dependent on the available sensors .
Priority
Source
1
Direct-wired outdoor temperature sensor (S1 and S2 terminals) .
2
Support Module 1, Sensor 1 configured as monitor .
3
OT assignment command .
If a query command is received and the node does not have an outdoor temperature sensor (direct-wired or via support module 1, sensor 1), it
responds with
SN[n] OT=--[scale]<CR>
. If an assignment command is received and the node does have an outdoor temperature
sensor, the command is ignored and no response sent .
The assignment command is used to allow one node to share the outdoor temperature sensor value . This is accomplished through the Host
controller by determining which node has the outdoor temperature then periodically sending a global outdoor temperature assignment
command to all other thermostats .
The Host controller must ensure that the outdoor temperature value is current . Otherwise, the thermostats without an outdoor temperature
sensor assume that the previously received value is no longer valid . The validity period is 10 minutes and is reset each time the Host
controller receives the temperature value from the node with the outdoor temperature sensor . If the validity period expires, the Host controller
sends a query command to the node with the outdoor temperature sensor to get the latest value then send a global outdoor temperature
assignment command to all other thermostats .
If more than one node has an outdoor temperature sensor, the Host controller uses the value from the lowest address .
If the value of the outdoor temperature changes by 1° or more, a C3 COS unsolicited message is issued (if C3 is ON) .
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