AMX VST User manual

instruction manual
HVAC Controls
ViewStat
Programming Protocol Reference Guide

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Table of Contents
i
ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Table of Contents
ViewStat Programming Protocol .............................................................................1
Network Communication ................................................................................................... 1
Explicit Address Commands .................................................................................................... 1
Global Address Commands ..................................................................................................... 2
Unsolicited Responses............................................................................................................. 2
Multiple Commands ................................................................................................................. 3
Network Override or Hold.................................................................................................. 4
How to Detect When a Thermostat Has Gone Off-line ............................................................ 4
Command Set Syntax ....................................................................................................... 5
Command Response Syntax............................................................................................. 5
Programming Quick Reference ......................................................................................... 6
Communication Control Commands ............................................................................... 10
Thermostat Sensing Commands.................................................................................... 15
Thermostat HVAC Operational Commands .................................................................... 18
Text Messaging Commands............................................................................................ 25
Text Messaging Support Characters...................................................................................... 25
Keypad Lockout Commands ........................................................................................... 30
Auxiliary Information Commands .................................................................................... 33

ii ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Table of Contents

ViewStat Programming Protocol
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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
ViewStat Programming Protocol
You can program the Viewstat to perform a wide variety of operations using SEND_STRING
commands. The Viewstat is designed to automatically echo each command you send to the
thermostat. For example, if you send a SEND_STRING HVAC "'SN9 SCALE?',13" command, the
system automatically echoes SN9=SCALE?. Then, the system will generate a reply when the
operation is complete that shows the current temperature scale. This section contains timing and
command descriptions, and lists communication control and thermostat commands.
For most applications, the NetLinx module for the ViewStat can be used, eliminating the need to
manually generate any code at all for the ViewStat. For detailed information on using the module,
refer to the ViewStat Communicating Thermostat Instruction Manual ("Using the NetLinx Module"
section), available on the AMX.COM web site.
Network Communication
Network communication is non-isolated, full duplex RS-422 using 4 + 1 wires. The 'A' terminals
are the transmit pair while the 'B' terminals are the receive pair. This nomenclature uses the host
computer as the reference, so transmit refers the lines on which the host transmits data to the
thermostat while receive refers to the lines on which the host receives data from the thermostat.
ASCII-based firmware, which is fully compatible with the StatNet command set, is defined below.
Up to 64 uniquely addressed devices are allowed on the network.
There are three response mechanisms depending on the nature of the command request:
! Explicit Address Commands
! Global Address Commands
! Unsolicited Responses
Explicit Address Commands
Explicit Address Commands are those commands that specify a single, particular address in the
command header (i.e. SN13 MODE=OFF). As this command is transmitted down the RS-422 bus,
each device connected will receive it into their buffer. The command will begin to be interpreted by
each device. Once the address is scanned, the entire command will be discarded if it is not that
unit's address. The unit that was explicitly addressed will complete the interpretation of the
command, act on it, and respond back to the host. Responses from an explicitly addressed
command can begin as quickly as 20 milliseconds after the command was sent, and not later than
330 milliseconds.
To communicate with the control system, set the baud to 9,600, data bits to 8, parity
to none, and stop bits to 1.

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2ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Global Address Commands
Global Address commands are those commands that do not specify any address in the command
header (i.e. SN T?). As with the Explicitly Addressed Commands described above, as this
command is transmitted, each device connected will receive it into their buffer. Since there is no
address, the units will recognize this as a global command. Each unit will complete the
interpretation of the command, act on it, and respond back to the host. However, unlike the Explicit
commands where only one unit will be responding, global commands imply that each unit will be
responding. Therefore the responses from global commands must be scheduled to prevent
collisions over the communications channel. Each device waits for its turn to issue its response.
The order of the response coincides with the unit address. Therefore the thermostat with address #1
will respond first, then #2, #3, on up to #64.
Responses from a global command can begin as quickly as 20 milliseconds after the command was
sent. The actual time lapse for the first response is dependent on the lowest addressed device on the
thermostat network. If there was no address #1 on the channel, then the first response opportunity
will be idle; simply passing time until the next response opportunity. Of course, if there is no
address #2 either, then there will be a delay as this opportunity passes. If no response begins within
265 * (Lowest Address) milliseconds, then one or more of the units did not understand the
command, the unit is in QUIET or SILENT mode, or is off-line. The last unit to respond will be the
unit with the highest address on the channel. Since the highest allowed address is 64, the longest
delay time for the start of the last response is approximately 17 seconds.
Unsolicited Responses
Change-Of-State (COS) responses are sent whenever a COS is detected for a condition specified in
the COS commands, when the COS has been turned "ON". There are twelve COS commands
described in detail in the Communication Control Commands section on page 10. COS responses
are sent so that a host computer connected to the thermostat network need not poll in order to see if
any thermostat variable change has taken place.
In unsolicited responses, no actual command has been sent down to solicit the response (once the
COS commands are sent, the unit will automatically respond on a change of state). Unsolicited
responses are scheduled according to address, in a similar manner to global responses. Each device
waits for its opportunity to come up, and issues its response at that time.
Unsolicited responses can begin as quickly as 20 milliseconds after the COS was detected. As with
global responses, unsolicited responses are issued only during the unit’s assigned opportunity. COS
responses will be received from a specific device no faster than X*265 milliseconds (X is defined
as the number of thermostats on the network, which is configurable in Thermostat Setup), since the
unit will only respond in its unique opportunity.
Do not skip addresses unless absolutely necessary to avoid unwanted delays in
responses.
Since the signal used to synchronize every device is the <CR> terminator of a
command, the host must issue a <CR> every 12 hours. Note that any command
send down the communications link from the host qualifies as a synchronizing
transmission.

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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Multiple Commands
Explicit commands, to one particular thermostat, can be issued and acted upon with no more than
20 milliseconds between each command. Responses must be received before moving to the next
thermostat to issue commands. Global commands can also be issued with no more than 20
milliseconds between commands if the Command Response (CR) has been set to Quiet (SN CR=Q)
or Silent (SN CR=S). Responses, stationed in a buffer awaiting the opportunity to be sent, can
create a backlog and cause incoming commands to be disregarded. If global commands are to be
sent with the Command Response set to Normal (SN CR=N), then the amount of time between any
set of two commands (the two commands must be separated by 20 milliseconds) must be 265
milliseconds times the "Number of Thermostats on the Network".
TIP: If responses are desired to a large number of commands, set the Command Response to Quiet,
send the commands (either globally or explicitly), then query individual thermostats (explicitly).
Return the command response to Normal when done. As an example consider a 64 thermostat
system. Now suppose the mode, fan, heat setting, cool setting and hold status were to be changed
on each thermostat. Further suppose that verification that all of these changes had been made were
required, and in addition the current temperature and remote temperature values were to be queried.
Using global commands, with the Command Response set to Normal, 17 seconds would be
required between each command. Five commands and two queries would be required (7 total
commands) requiring a total time of approximately two minutes.
Sending five commands and seven queries to each thermostat explicitly would require
approximately 37 seconds.
To maximize communication speed consider the following:
1. Communicate at 19200 baud
2. Do not skip addresses on the thermostat network unless absolutely necessary.
Global Command Sequence: Explicit Command Sequence
SN M=A SN CR=Q
SN F=A SN M=A
SN SH=70 SN F=A
SN SC=75 SN SH=70
SN HOLD=OFF SN SC=75
SN T? SN HOLD=OFF
SN OT? SN1 M?
SN1 F?
SN1 SH?
SN1 SC?
SN1 HOLD?
SN1 T?
SN1 OT?
SN2 M?
:
SN64 OT?
SN CR=N

ViewStat Programming Protocol
4ViewStat Communicating Thermostat - Programming Protocol Reference Guide
3. Set the "Number of Thermostats on the Network" to the highest addressed thermostat. If you
have only six thermostats address them 1 through 6 and set the highest address to six.
4. Only turn on the necessary change of state variables (COS - refer to the command
descriptions).
5. Send commands explicitly when possible.
6. When sending a large number of commands, set the Command Response to Quiet. If
responses are needed, explicitly query each thermostat on the network.
Network Override or Hold
Invoking Network Override causes the thermostat to disregard all received commands except
requests for data. This means that no response will be forthcoming. Network Override can be
invoked at the thermostat (by using the Enter button) or through the command set (SN HOLD=ON).
Unsolicited data transmission is unaffected. Should the thermostat be receiving communication
when Network Override is invoked, the reaction will be carried out following the reaction caused
by the communication signal.
If receiving no response to a command will cause disruption to your program, then there are two
options: disable this feature or begin every command transmission by "SN HOLD=OFF". To disable
the feature, ensure that Hold is "OFF" at each thermostat and send the command "SN NETLK=1".
Alternatively it could be disabled through the Thermostat Set Up menu.
How to Detect When a Thermostat Has Gone Off-line
When a thermostat goes off-line (re-initializes) the Change of State (COS) variables return to
default values - OFF. The consequence of this occurring is that unsolicited responses will not be
sent by the thermostat (i.e. the automation system will not know when something has been changed
at the thermostat). There are two reasons that a thermostat will have gone off-line: the power had
been removed and reinstated or the Thermostat Set Up menu has been entered. When this occurs
the COS variables must be reset. It is good practice to periodically check (once every 15 minutes is
a good start) that all thermostats are still responding. Simply query one of the COS variables you
have turned on to verify it is still on. For example periodically send the command "SN C2?". You
should receive the response "SNx C2=ON"; where xis the address of each thermostat on the
network.

ViewStat Programming Protocol
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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Command Set Syntax
SN#[COMMAND][? OR =][VALUE] <CR>
Upper or lower case letters may be used for all commands. Invalid characters will immediately
invalidate a command, so the use of delete is not allowed (applies mainly when interacting with the
thermostat using HyperTerminal).
All Viewstat commands will begin with the characters SN. Immediately following the SN, without
any intervening spaces (blanks), will be the address (#) from 1 to 64 of the Viewstat with which you
are communicating. Single digit addresses may be sent as a two digit address with a leading zero.
Omitting the address, or using a 0 (zero) in place of a space makes the command global, and all
connected thermostats will respond. Following this initial command sequence, spaces may be
inserted at this point only, for clarity between commands. The next portion is the command or
variable [Command]. The table below describes the available commands. The next portion
[? Or =] is the action to be performed: ?corresponds to "state your value", =corresponds to "set
your value". Spaces are allowed between the command and the action. The final portion,
[Value], is used only if a command or variable is to be set.
The value must follow the action with no intervening spaces. A carriage-return <CR> (Enter) is
used as the terminator for the command string. Line feeds (LF) should not be sent with commands
as this is a recognized ASCII character and invalidates any command received between the line
feed and the next carriage return.
EXCEPTIONS: The command SN? or SN0? will respond with all connected thermostats returning
their address. The command BLTON performs its intended action without the need for a value.
Command Response Syntax
The ViewStat responds by supplying the information requested or by confirming the completion of
an action command. The response syntax is generally the same as that used for commands, but no
spaces separate command, action or value. Responses are sent in upper case ASCII format. Details
of the response can be found in the detailed description section for each command. Should a
command not be recognized, no response will be forthcoming - there is no ERROR message.

ViewStat Programming Protocol
6ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Programming Quick Reference
All of the commands are summarized in the following list. A detailed description of each
command follows the table. Unless otherwise noted as "Read Only" or "Write Only", all
commands are "Read and Write".
Programming Quick Reference
Command Description Value
Communication Control Commands
CR Command Response Control Silent / Quiet / Normal
C1 Change of State (COS) - HVAC relays ON/OFF
C2 COS - Temperature ON/OFF
C3 COS - Remote Temperature ON/OFF
C4 COS - Contact Closures ON/OFF
C5 COS - Set Points ON/OFF
C6 COS - Network Override ON/OFF
C7 COS - Mode ON/OFF
C8 COS - Fan ON/OFF
C9 COS - Scroll Up activation ON/OFF
C10 COS - Scroll Down activation ON/OFF
C11 COS - Enter Button activation ON/OFF
C12 COS - Backlight Ready ON/OFF
CP Command Configuration Pattern 1 / 2
HOLD User Hold Status ON / OFF
NAME Location Name <String>
ID Report Model No. and software rev. Read Only
BAUD Specifies thermostat communication baud
rate.
9600, 19200
Thermostat Sensing Commands
SCALE Command Temperature Scale F / C (Fahrenheit/Celsius)
CT Controller Type; Temperature or Humidity. Set
to Humidity only when auxiliary humidity con-
trol sensor is detected.
• 0 = Temperature controller
• 1 = Humidity controller
Read Only
TEMP, T Report Thermostat Room Temperature Read Only
HUM Report Thermostat Room Humidity Read Only
RSM Identify all remote sensors connected to a ther-
mostat's local communication network
Read Only
RxSy
(x = 1-4;
y = 1,2)
Report value of any sensor on thermostat's
local communication network
Read Only
OT Report Thermostat Remote (outdoor) Temper-
ature
Read Only
RReport Thermostat Remote (outdoor) Temper-
ature
OH Report Thermostat Remote Humidity Read Only
(Cont.)

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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Programming Quick Reference (Cont.)
Command Description Value
Thermostat HVAC Operational Commands
SH Heat Mode Set Point Two digit integer: 40 - 88 for °F;
4 - 31 for °C
SH++ Increment heat set point Integer value which when added to the cur-
rent heat set point does not fall outside the
SH limits
SH-- Decrement heat set point Integer value which when deducted from
the current heat set point does not fall out-
side the SH limits
SC Cool Mode Set Point Two or three digit integer: 42 - 90 for °F;
6 - 33 for °C
SC++ Increment cool set point Integer value which when added to the cur-
rent cool set point does not fall outside the
SC limits
SC-- Decrement cool set point Integer value which when deducted from
the current cool set point does not fall out-
side the SC limits
SCurrent Mode Set Point Two or three digit integer (see next two
commands)
SP++ Increment current mode set point Integer value which when added to the cur-
rent mode set point does not fall outside
the SH and SC limits
SP-- Decrement active set point Integer value which when deducted from
the current mode set point does not fall out-
side the SH and SC limits
DIF1 Temperature control differential for 1st stage
heat/cool.
0.5° - 2° in 0.5° increments
DIF2 Temperature control differential for 2nd stage
heat/cool.
0.5° - 2° in 0.5° increments
OFFSET Amount to offset the display temperature from
the sensed temperature.
±3°, 1° increments
SHUM Humidify Mode set point Two digit integer: 10-90
SHUM++ Increment humidify set point Integer value which when added to the cur-
rent humidify set point does not fall outside
the SHUM limits
SHUM-- Decrement humidify set point Integer value which when deducted from
the current humidify set point does not fall
outside the SHUM limits
SDEH Dehumidify Mode set point Two digit integer: 10-90
SDEH++ Increment dehumidify set point Integer value which when added to the cur-
rent dehumidify set point does not fall out-
side the SDEH limits
SDEH-- Decrement dehumidify set point Integer value which when deducted from
the current dehumidify set point does not
fall outside the SDEH limits
MODE,M Thermostat Mode of Operation A / C / H / E / OFF
(Auto/Cool/Heat/EMHT/Off)
Humid/Dehum when operating as a humid-
ity controller.
FAN, F Fan Switch Setting A / ON (Auto/On)
HVAC, H Report HVAC Relay States Read Only
(Cont.)

ViewStat Programming Protocol
8ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Programming Quick Reference (Cont.)
Command Description Value
Thermostat HVAC Operational Commands (Cont.)
HIBP Temperature value above which W1 terminal
is locked out (heat pump equipment configura-
tion only).
40° - 80°, 5° increments
LOBP Temperature value below which compressor
terminals are locked out (heat pump equip-
ment configuration only).
0° - 40°, 5° increments
Text Messaging Commands
DATE Thermostat date value MMDDYY
TIME Thermostat time value HHMM
PMES1 1st message in the permanent message
sequence
32 character text string
PMES2 2nd message in the permanent message
sequence
32 character text string
PMES3 3rd message in the permanent message
sequence
32 character text string
PMES4 4th message in the permanent message
sequence
32 character text string
TMPMES Temporary message 32 character text string
MENU Operates the text messaging display in a User-
Interactive mode. MSG is used to display mes-
sages when MENU is on.
ON/OFF
MSG User-Interactive message 32 character text string
Keypad Lockout Commands
FANLK Determines the degree to which the user is
locked out of fan control.
0=no lockout,
1=time limited change,
2=total lockout
MODELK Determines the degree to which the user is
locked out of mode control.
0=no lockout,
1=time limited change,
2=total lockout
NETLK Determines the degree to which the user is
locked out of network override control.
0=no lockout,
1=total lockout
UPDNLK Determines the degree to which the user is
locked out of increment/decrement control.
0=no lockout,
1=time limited change,
2=time and value limited change,
3=total lockout
LKTIME Time value (minutes) that an input change is
allowed until it reverts back to the pre-change
value.
Integer value between 0 and 255
LKLIMIT Number limit that the increment/decrement is
allowed to change when locked.
Integer value between 0 and 20
Monitoring Module Commands
CC Digital Input States All of these commands will simply return a
response - no action at the thermostat
occurs. If inquired all will respond as
though all inputs/outputs/led's are OFF.
CO Digital Output States
Ln
(n = 1 to 4)
Comm. Card LED Light 1,2,3 or 4
(Cont.)

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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Programming Quick Reference (Cont.)
Command Description Value
Auxiliary Information Commands
EQUIPCONFIG Reports the setting of the thermostat configu-
ration DIP switches
Read Only
BLREADY Reports ready state of photosensor 0 = Backlight in ready state,
1 = Backlight not in ready state.
BLTRIG Sets relative room light intensity level required
to put backlight in ready state
0 = darker,
1=lighter
BLTON Turns on backlighting, regardless of ready
state, for 10 seconds.
No value required for this command
ENTR Enter button status 1 = State change from inactive to active,
0 = State change from active to inactive
SCUP Scroll Up button status 1 = State change from inactive to active,
0 = State change from active to inactive
SCDN Scroll Down button status 1 = State change from inactive to active,
0 = State change from active to inactive

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10 ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Communication Control Commands
The following commands control how the ViewStat will communicate.
The following command descriptions describe the use of the command when setting a particular
variable. Inquiries can be made with all commands (with the exception of the SCUP, SCDN, BLTON
and ENTR commands) to determine the existing value of a variable. Inquiry is done using the
following syntax:
SN [address number, or <blank> or 0 (zero) for global] "COMMAND" ?
where COMMAND is the variable whose value is desired.
Communication Control Commands
Command Description
CR
Command Response Control
The ViewStat normally responds to all commands. All responses begin with the
string SNx where xis the ViewStat network address number (address range =
1-64). All responses are concluded with a carriage return. The Command
Response Control command allows you to change the response actions.
Syntax:
"'SN<address> CR=<mode>'"
Variables:
•<address> = 0 (all thermostats), or 1 through 64 (thermostat-specific
address)
•<mode> = S, N, Q
S(SILENT) - Viewstat will not reply to any command. Action commands
(telling ViewStat to change a setting) will be acted upon, but no response will
be returned indicating that the action was performed. All inquiry commands
(asking ViewStat for information) will be ignored. COS commands will be
received by ViewStat, but ViewStat will not act upon those commands while in
the silent mode.
N(NORMAL) - sets the ViewStat to the default mode where a response is
always given.
Q(QUIET) - Viewstat will not reply to action commands. Inquiry commands
will be responded to. This suppresses the feedback response on action
commands. COS commands will be heard and carried out.
Example 1 - Silent mode
• Command Format:
SN[address] CR=S or SILENT
• Reply Format: No response will be received.
Example 2 - Normal mode
• Command Format:
SN[address] CR= N or NORMAL
• Reply Format:
SN[address number] CR=NORMAL
Example 3 - Quiet mode
• Command Format:
SN[address] CR= Q or QUIET
• Reply Format: No response will be received.
(Cont.)

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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Communication Control Commands (Cont.)
Command Description
(C1 - C12) Change-Of-State (COS) notify commands:
The ViewStat can be configured to send out a message upon a Change-Of-State (COS) for any of the variables
below. Simply turn on the COS flag for any of the variables for which the automation system needs to be kept
informed. In this way, a computer connected to Eclipse need not poll in order to see if anything has occurred -
it can simply ignore the ViewStat until it hears from it. The computer will only be notified if some event takes
place at the thermostat unit. If all COS flags are set to OFF, the Eclipse will not report anything automatically,
and the computer unit must send inquiries to the ViewStat to determine any new conditions. (This equates to a
'polling' mode, whereas with any COS flag ON equates to an interrupt mode.) There are twelve COS
indicators, which by default, are set OFF on power-up or reset.
The command format for COS notify commands is:
SN[address number or <blank> for global] C1 through C12=ON or OFF
The reply format:
SN[address number] C1 through C12=ON or OFF
Each of the COS notify commands and their responses are described in the following cells.
C1
COS - HVAC Control Circuits
When any thermostat output goes from an energized state to a de-energized
state or vice versa.
Example of response:
SN1 HVAC = G+Y1+W1-Y2-W2-B-O+
C2
COS - Temperature or
Humidity
When the thermostat room temperature (or humidity) reading changes.
Examples of response:
SN3 T = 72F
SN6 HUM = 36%
C3
COS - Remote Temperature
or Humidity
When the thermostat remote temperature (or humidity) reading changes.
Examples of response:
SN15 OT = 86F
SN4 OH = 57%
C4
COS - Contact Closures
Applies to Monitoring Module output status.
C5
COS - Thermostat Set Points
When the thermostat Heat, Cool, Humidify or Dehumidify temperature setting is
changed by use of the up and down buttons on the thermostat.
Examples of response:
SN1 SH = 68F
SN5 SC = 78F
SN13 SHUM = 32%
SN4 SDEH = 65%
C6
COS - Network Override
(Hold) Function
When thermostat network control has been overridden or returned at the ther-
mostat.
Example of response:
SN1 HOLD = ON
C7
COS - Thermostat Mode
When the mode of operation (i.e. Heat, Cool, Auto, Off or Emergency Heat) has
been changed by use of the thermostat Mode button.
Syntax:
SN<address> C7=<value>
Example of response: SN3 M = AUTO
C8
COS - Thermostat Fan State
When the fan is changed to On or Auto by use of the thermostat Fan button.
Example of response: SN2 F = AUTO
(Cont.)

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12 ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Communication Control Commands (Cont.)
Command Description
C9
COS - Scroll Up (thermostat
button)
When the scroll-up button (top button next to the text messaging display) is
pressed or released.
Example of response:
SN4 SCUP = ON
SN4 SCUP = OFF
C10
COS - Scroll Down (thermo-
stat button)
When the scroll-down button (bottom button next to the text messaging display)
is pressed or released.
Example of response:
SN5 SCDN = ON
SN5 SCDN = OFF
C11
COS - Enter Button activation
When the ENTER button is pressed or released.
Example of response:
SN3 ENTR = ON
SN3 ENTR = OFF
C12
COS - Backlight Ready
When the thermostat backlight enters the ready state (i.e. room illuminance
less than that set at the thermostat).
Example of response: SN1 BLREADY = ON
(Cont.)

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ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Communication Control Commands (Cont.)
Command Description
CP
Command Configuration Pat-
tern
Set the default (CP=1) or custom (CP=2) control system configuration pattern.
The ViewStat can retain two independent sets of communication configuration
settings. Each set contains the state of all Change-Of-State (COS) settings
and the Command Response (CR) setting. Default values for CP #1 and CP #2
are shown below.
IMPORTANT: Once a configuration pattern has been selected, any changes
you make to the communications control commands are assigned to the active
configuration pattern.
By default, CP #1 is active upon startup. The benefit of this command is to
facilitate having a standard configuration for normal operation and a second
configuration for special functions. CP #2 is convenient for those who wish to
integrate the text messaging display into their automation system. You may
alternate between these two configurations by simply sending the Configuration
Pattern command.
Syntax:
SN[address] CP=<pattern>
Parameters:
•<address> = 0 (global), or 1 through 64 (thermostat-specific address)
•<pattern> = 1 or 2
Reply Format:
SN[address number] CP=1 or 2 No response sent when set to CP=1
(i.e. no response to SN1 CP=1)
HOLD
Network Override
Syntax:
SN[address] HOLD=ON or OFF
Parameters:
•<address> = 0(all thermostats), or 1 through 64 (thermostat-specific
address)
The ViewStat incorporates an ENTER button. This button has three functions:
•Thermostat Set-up - During Thermostat Set-Up the user interacts with the text
messaging display to select various operational parameters and this button is
used to enter those selections.
•User Reset Message Resetting - When the thermostat receives a User Reset
Message command this button is used clear the message from the text
messaging display.
•Network Override - During all other times, this button is used to override
network control of the thermostat: temperature changes, mode changes and
fan state changes are controlled only by the buttons on the thermostat.
This command can be used to change the Network Override status or HOLD
status regardless of what the text messaging display is doing. When activated
(HOLD = ON), "NETWORK OVERRIDE" shows on the ViewStat display. The
NETLK command enables or disables this feature.
Default Settings for
Configuration Pattern 1:
CR = Normal
C1 = Off
C2 = Off
C3 = Off
C4 = Off
C5 = Off
C6 = Off
C7 = Off
C8 = Off
C9 = Off
C10 = Off
C11 = Off
C12 = Off
Default Settings for
Configuration Pattern 2:
CR = Normal
C1 = Off
C2 = Off
C3 = Off
C4 = Off
C5 = Off
C6 = Off
C7 = Off
C8 = Off
C9 = On
C10 = On
C11 = On
C12 = Off
(Cont.)

ViewStat Programming Protocol
14 ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Communication Control Commands (Cont.)
Command Description
NAME
Location Name
You can have the ViewStat append an identifier name to its address when it
transmits a message. The identifier string must be 16 characters or less with
no spaces.
Syntax:
SN[address] NAME={text string}
Parameters:
•<address> = 0(all thermostats), or 1 through 64 (thermostat-specific
address)
• <text string> = text string used as an identifier for the specified thermostat.
String must be 16 characters or less - no spaces allowed.
Reply Format:
SN[address number]{NAME}
Example:
• Set a name to the thermostat with address #1:
SN1 NAME=MASTER BEDROOM<CR>
Response:
SN1MASTER BEDROOM (ViewStat confirms that a new name is assigned).
• Inquire temperature at thermostat #1:
SN1 T?<CR>
Response:
SN1MASTER BEDROOM T=72F (ViewStat responds with the temperature at
thermostat #1, now called Master Bedroom).
• Clear the name of the thermostat with address #1:
SN1 NAME=<CR>
Response:
SN1 (ViewStat confirms that the name has been removed).
ID
Report Thermostat Model
Number and Software Revi-
sion Number
Eclipse will respond with the model number followed by the current software
revision.
Syntax:
SN[address] ID?
Reply Format:
SN[address] MODEL# 8870 REV: x.x RPC 2001;
Parameters:
•<address> = 0(all thermostats), or 1 through 64 (thermostat-specific
address)
•x.x = the current firmware revision level.

ViewStat Programming Protocol
15
ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Thermostat Sensing Commands
These commands are used to inquire and set scale for the various temperature or humidity values
read by the thermostat
The following command descriptions describe the use of the command when setting a particular
variable. Inquiries can be made with all commands (with the exception of the SCUP, SCDN, BLTON
and ENTR commands) to determine the existing value of a variable. Inquiry is done using the
following syntax:
SN [address number, or <blank> or 0 (zero) for global] "COMMAND" ?
where COMMAND is the variable whose value is desired.
Thermostat Sensing Commands
Command Description
SCALE
Set Temperature Scale
Thermostat temperature readings can be displayed and communicated in either Cel-
sius (Centigrade) or Fahrenheit as dictated by this command. The setting at initial
power up will default to °F. Subsequent start-ups (i.e. loss of power or resets) will
default to the scale that was last set. Scale setting applies to the room temperature,
the remote temperature and all temperature settings. When a temperature setting is
to be communicated to the thermostat, and no scale is designated, the temperature
will be read using the scale that has been set for the thermostat.
Syntax:
SN[address] SCALE=F or C
Reply Format:
SN[address] SCALE=F or C
CT
Controller Type
Connecting an optional support module, configured for humidity control, to the View-
Stat changes it from a temperature controller to a humidity controller. Controller type
is a read-only command. This command is used to determine which ViewStat ther-
mostats connected to the network are currently acting as temperature controllers or
humidity controllers.
The response designations are CT=0, for temperature controller or CT=1, for humidity
controller.
Syntax:
SN[address] CT?
Reply Format:
SN[address] CT=0 (temperature controller) or 1 (humidity
controller)
TEMP
Thermostat Tempera-
ture
Thermostat temperature is that shown on the display of the thermostat and against
which the temperature settings are compared for control purposes. This temperature
can be from the thermostat's on-board temperature sensing element or from attached
support module(s) configured for temperature control. ViewStat responds with the
temperature in the scale set by the SCALE command. It appends a Cor Fto the value
for clarity.
Syntax:
SN[address] TEMP?
Reply Format:
SN[address] T={value}F or {value}C

ViewStat Programming Protocol
16 ViewStat Communicating Thermostat - Programming Protocol Reference Guide
Thermostat Sensing Commands (Cont.)
Command Description
HUM
Thermostat Humidity
Connecting an optional support module, configured for humidity control, to the View-
Stat changes it from a temperature controller to a humidity controller. Thermostat
humidity is that shown on the display of the thermostat and against which the humidity
settings are compared for control purposes. This humidity reading is that measured
attached support module(s) configured for humidity control. ViewStat responds with
the humidity reading appended by a "%" for clarity.
Syntax:
SN[address] HUM?
Reply Format:
SN[address number] H={value}%
RSM
Remote Sensor Mod-
ules
Up to four addressable support-modules can be connected to a thermostat's local
communication network (LCN). Two sensors can be connected to each support mod-
ule, each can be a temperature sensor or a humidity sensors depending on the sup-
port module model. Each sensor can be individually configured as control sensors or
remote sensors (for display only). This command returns the number of support mod-
ules connected to a thermostat, what type of sensors are attached to them and how
those sensors are configured.
Syntax:
SN[address] RSM?
Reply Format:
SN[address] RSM= M1:S1,S2 M2: S1,S2 M3: S1,S2 M4: S1,S
The response is made up of the number of modules (Mx) and the type of each of the
two sensors connected to that module (RT, CT, RH, CH or XX). The first sensor listed is
considered sensor #1 for that module and the second listed is considered sensor #2.
If there is no support module at a module address then it will not be shown. S1,S2
show what type of sensor is connected as sensor #1 and Sensor #2 respectively.
Sensor (S1, S2) options include:
•RT: Remote temperature sensor (i.e. for display only)
•CT: Control temperature sensor (i.e. replaces control value of thermostat)
•RH: Remote humidity sensor
•CH: Control humidity sensor
•XX: No sensor attached at this position
Following is an example that illustrates the response (commands are bold responses
are shown in italics):
SN1 RSM?
(Request information about sensors connected to thermostat with address #1.)
SN1 RSM= M1:RT,RT M2:CT,CT M3:RH,CT
(ViewStat responds that there are three support modules attached to thermostat 1,
that there are two remote temperature sensors on the module with address #1, two
control temperature sensors on the module with address #2 and that the module
with address #3 has a remote humidity sensor as sensor #1 and a control
temperature sensor as sensor #2).