instruction manual ViewStat Programming Protocol Reference Guide H VA C C o n t r o l s
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Table of Contents Table of Contents ViewStat Programming Protocol .............................................................................1 Network Communication ................................................................................................... 1 Explicit Address Commands .................................................................................................... 1 Global Address Commands .........................................................................................
Table of Contents ii ViewStat Communicating Thermostat - Programming Protocol Reference Guide
ViewStat Programming Protocol 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.
ViewStat Programming Protocol 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.
ViewStat Programming Protocol 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).
ViewStat Programming Protocol 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.
ViewStat Programming Protocol Command Set Syntax SN#[COMMAND][? OR =][VALUE] 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.
ViewStat Programming Protocol 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".
ViewStat Programming Protocol Programming Quick Reference (Cont.
ViewStat Programming Protocol Programming Quick Reference (Cont.) Command Description Value Thermostat HVAC Operational Commands (Cont.) HIBP Temperature value above which W1 terminal 40° - 80°, 5° increments is locked out (heat pump equipment configuration only). LOBP Temperature value below which compressor terminals are locked out (heat pump equipment configuration only).
ViewStat Programming Protocol Programming Quick Reference (Cont.) Command Description Value Auxiliary Information Commands EQUIPCONFIG Reports the setting of the thermostat configuration DIP switches Read Only BLREADY Reports ready state of photosensor 0 = Backlight in ready state, BLTRIG Sets relative room light intensity level required to put backlight in ready state 0 = darker, BLTON Turns on backlighting, regardless of ready state, for 10 seconds.
ViewStat Programming Protocol 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.
ViewStat Programming Protocol 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.
ViewStat Programming Protocol Communication Control Commands (Cont.) Command Description C9 When the scroll-up button (top button next to the text messaging display) is pressed or released. COS - Scroll Up (thermostat button) Example of response: SN4 SCUP = ON SN4 SCUP = OFF C10 COS - Scroll Down (thermostat button) When the scroll-down button (bottom button next to the text messaging display) is pressed or released.
ViewStat Programming Protocol Communication Control Commands (Cont.) Command Description CP Set the default (CP=1) or custom (CP=2) control system configuration pattern. Command Configuration Pat- The ViewStat can retain two independent sets of communication configuration tern 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.
ViewStat Programming Protocol Communication Control Commands (Cont.) Command Description 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. Location Name Syntax: SN[address] NAME={text string} Parameters: •
= 0 (all thermostats), or 1 through 64 (thermostat-specific address) • = text string used as an identifier for the specified thermostat.ViewStat Programming Protocol 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.
ViewStat Programming Protocol Thermostat Sensing Commands (Cont.) Command Description HUM Connecting an optional support module, configured for humidity control, to the ViewStat 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 Programming Protocol Thermostat Sensing Commands (Cont.) Command Description RxSy 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 module. This value is used to retrieve the value of the sensor in the appropriate units of measure. The 'RSM' command is used to determine what sensors of what type are available on the thermostat LCN.
ViewStat Programming Protocol Thermostat HVAC Operational Commands These commands are used for temperature control and other thermostat operational parameters. 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.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description SC++/SC -- These commands are used to raise (SC++) or lower the (SC--) the cool temperature setting by a specified value. The value is assumed to be in the temperature scale set using the SCALE command and the response will include a scale designator. Should the resultant change be outside the allowable range for the set temperature scale, the command will be ignored.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description DIF1, DIF2, & OFFSET Three temperature control variables can be accessed through the ViewStat command set; they are first stage differential (DIF1), second stage differential (DIF2) and display temperature offset or bias (OFFSET). Temperature Control Configuration Settings The ViewStat is an on/off type temperature controller.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description SHUM++/SHUM - - These commands are used to raise (SHUM++) or lower the (SHUM--) the humidify setting by a specified value. Should the resultant change be out of the allowable humidify setting limits, the command will be ignored.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description MODE This command dictates what equipment the thermostat will turn on/off to control temperature. In the HEAT mode, only the heating equipment will be used, in the COOL mode, only the cooling equipment will be used. When the thermostat has been configured to operate a heat pump (this is a DIP switch configuration on the thermostat), Emergency Heat (EMHT) mode is available.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description HVAC Thermostats control HVAC units by energizing various relays within the thermostat completing a circuit to the HVAC controls. This command reports the on or off state of each relay within the thermostat. Report HVAC Relay States Syntax: SN[address] HVAC? Reply Format: SN[address] HVAC=G±Y1±W1±Y2±W2±B±O± (see example below) The relay names used are consistent with HVAC terminology.
ViewStat Programming Protocol Thermostat Action Commands (Cont.) Command Description HIBP & LOBP Heat pumps, when operating in the heating mode, extract heat from the outdoor air and transfers it to the indoor air. An auxiliary source of heat is High And Low Balance Point (Applicable Only For Heat Pumps) usually present on heat pump systems to meet the heating demand when the heat pump can not meet the capacity needs.
ViewStat Programming Protocol Text Messaging Commands ViewStat incorporates two displays, a segmented display and a two-line, 16-character per line text messaging display. These commands are used to control the text messaging display. Text Messaging Support Characters FIG. 1 shows the correspondence between character codes and character patterns.
ViewStat Programming Protocol Text Messaging Commands Command Description DATE ViewStat has a counter and can maintain a clock, once set, with reasonable accuracy over a 24-hour period. Therefore it is necessary to send ViewStat the current Date and Time from the automation system at least once per day. Each variable, Date and Time, has its own command.
ViewStat Programming Protocol Text Messaging Commands (Cont.) Command Description TIME The ViewStat has a counter and can maintain a clock, once set, with reasonable accuracy over a 24 hour period. Therefore it is necessary to send ViewStat the current Date and Time from the automation system at least once per day. Each variable, Time and Date, has its own command. Text Messaging Display - Time Time is sent as a four digit integer with 0000 corresponding to midnight, and 2359 corresponding to 11:59 p.
ViewStat Programming Protocol Text Messaging Commands (Cont.) Command Description PMES1 - PMES4 ViewStat can store and display up to four messages on a rotating basis. The text messaging display is a two-line, 16-character display. The first character in the top line of the display is filled with the first character in the text string of the command. The remainder of the character spaces are filled across the top line and then down and across the bottom line.
ViewStat Programming Protocol Text Messaging Commands (Cont.) Command Description TMPMES With this command messages can be shown on the text messaging display that must be acknowledged by the user at the thermostat to reset. Examples of this type of message might be that it is time to change a filter or call for service. The text messaging display is a two-line, 16-character display. The first character in the top line of the display is filled with the first character in the text string of the command.
ViewStat Programming Protocol Keypad Lockout Commands Use of the buttons on the thermostat can be locked out to varying degrees using the following commands. 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.
ViewStat Programming Protocol Keypad Lockout Commands (Cont.) Command Description NETLK ViewStat incorporates an ENTER button, which has three functions: Network Override (Hold) Lockout • User Interactive 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.
ViewStat Programming Protocol Keypad Lockout Commands (Cont.) Command Description LKTIME Thermostat functions can be locked out to thermostat keypad changes to various levels. One of those levels allows changes for a period of time determined by the LKTIME command.
ViewStat Programming Protocol Auxiliary Information Commands These commands are used to request information regarding miscellaneous thermostat parameters. Auxiliary Information Commands Command Description EQUIPCONFIG Four DIP switches are available on the thermostat circuit board, three to configure the thermostat for type of equipment it is to be used with and one to designate a thermostat as a "master". The position of these switches can be read using this command.
ViewStat Programming Protocol Auxiliary Information Commands (Cont.) Command Description BLTRIG A photosensor is integrated on the thermostat circuit board to put the display backlighting (both the segmented display and the text messaging display) in a ready state depending on the intensity of the ambient light. This command is used to select a relative intensity.
ViewStat Programming Protocol ViewStat Communicating Thermostat - Programming Protocol Reference Guide 35
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