Metasys Network Technical Manual 636 Glossary Section Technical Bulletin Issue Date 1092 Glossary Access Controller object The hardware object that defines the interface between the D600 Controller and the NCM. Accumulator (ACM) object The software representation of a binary input device that measures flow or consumption by monitoring a rate of contact or voltage change. ACM See Accumulator object. active hub A multi-port repeater used in an N1 LAN star or mixed network configuration to transmit messages and to provide electrical isolation for each node in the network. active link A 2-port repeater used in an N1 LAN or mixed network configuration if the signal must be regenerated. AHU Controller An Application Specific Controller used for Air Handling Unit (AHU) operations. The AHU may be used as a standalone unit, or connected to the N2 Bus as an element in a Metasys Network. alarm latching The capability of defining a Binary Input object or a Binary Data object as a latching point. When an alarm condition occurs, the object remains in the alarm state until an operator or control process issues an Unlatch command. Analog Data (AD) object A point object derived from an analog value that was obtained as the result of a control process, operator entry, or attribute from another object. Analog Input (AI) object The software representation of a hardware device that is monitoring an analog value. Analog Output Digital (AOD) object The software representation of a control output used in positioning valves, dampers, and other proportional devices. The AOD object is generally used in conjunction with the PID Loop object. © 1992 Johnson Controls, Inc. Order No. 636-355 1 Analog Output Setpoint (AOS) object The software representation of an analog output device used in position control or remote setpoint adjustment. Application Specific Controller (ASC) A family of standalone control devices with hardware and software preconfigured to meet the functional needs of a specific application. ARCNET The 2.5 megabit/sec., token-passing Local Area Network protocol developed by Datapoint Corporation. A baseband network, which transmits digital signals one message at a time. The Metasys N1 LAN uses ARCNET. ASC See Application Specific Controller. attribute A characteristic or property of an object (e.g., a low limit of an analog point) that describes the object status and makes it unique. AUTO A command that releases the Override command and allows other lower priority inputs to change the current value. Auto Restore A function that restores a device to its correct commanded condition when either communication is resumed after a failure or the NCM is restarted. Binary Data (BD) object A point object derived from a binary value that was obtained as the result of a control process, operator entry, or attribute from another object. Binary Input Alarm Point One of up to eight binary inputs attached to a Smart Terminal Interface (STI). Binary input alarm points are used to identify breaches in security. Binary Input (BI) object The software representation of a Binary Input device that is monitoring a 2-state (On/Off) field condition. Binary Output (BO) object The software representation of a 2-state (On/Off) controlled device. Blink An optional user-programmable feature of an Intelligent Lighting Controller that momentarily turns Off the lights in a lighting group to notify occupants that the lights are about to be turned off. Buffer Process of temporarily storing data in register or in RAM, that allows transmission devices to accommodate differences in data rates and to perform error checking and re-transmission of data received in error. bumpless transfer A software feature that tracks the difference between setpoint and feedback, then gradually resolves the differences to reach setpoint when control changes from manual to automatic operating modes. 2 Glossary bus A transmission path wherein devices on a given medium receive all transmissions at the same time, but process only those addressed to them. bus network One of three available configurations for the Metasys N1 LAN. The bus network configuration consists of a layout in which the nodes are connected in a daisy chain fashion. C210 Controller A preprogrammed Application Specific Controller with standalone capabilities used primarily for the monitoring and control of Variable Air Volume (VAV) box controllers. C260 Controller A preprogrammed Application Specific Controller with standalone capabilities used primarily for water source heat pump control. CAL1 (Custom Applications Language One) A programming language used to define the programs and data base of the DSC-8500 hardware object. Card Reader A device that translates information on an access card and sends it, via a Smart Terminal Interface (STI), to the D600 Controller data base for verification. Up to 16 card readers can be included in an IAC-600 Access Control System. Card Reader object A software object that represents one Smart Terminal Interface/Card Reader combination in an IAC-600 Access Control System. Change-of-State (COS) For a point object, the act of transferring from one condition to another in realtime (e.g., a Binary Input point object changing from Normal to Alarm). Change-of-State Reporting Passing of a COS event to an Input/Output (I/O) device for priority display. Cleaning Crew An ILC feature that interlocks lighting groups so janitorial crews can turn On assigned lighting groups in the area about to be cleaned. This automatically turns Off lights in the previous cleaning area. Cold Start Restarting the Network Control Module so that it is operating out of Erasable Programmable Read-Only Memory (EPROM) based code. When the Network Control Module is cold started, both code and data need to be downloaded and stored within Dynamic Random-Access Memory (DRAM) to return to normal operations. Contrast with warm start. Glossary 3 Communication Terminal Board (TBC) A termination board that allows NCU communication across the N1 LAN. The board also terminates the N2 and L2 Buses to the NCU/NEU. connectivity The ability to link together two or more computers or systems for the purpose of communication, data transfer, etc. control object The name of the software definition of a specific process that combines multiple field devices (point objects) to perform a function. Control System (CS) object The software representation of selected hardware and internal points in an Application Specific Controller (ASC). Typically, the CS object represents one control strategy (e.g., temperature control or static pressure control) located in a controller, though it may represent more than one strategy. COS See Change-of-State. D600 Controller The IAC-600 System intelligent access controller, which performs security management functions within Metasys. Data Base Manager A collection of subroutines (program code) used to read from and write tasks to object records, feature records, and control strategy records. Data Definition Language (DDL) Text-oriented software program for creating global and object data bases. DDA See Dynamic Data Access. DDE See Dynamic Data Exchange. DDL See Data Definition Language. deadband See normalband. definable The capability of being defined, applies to attributes of an object that the operator may set a value for. For example, when you enter a System Name and Object Name for an object, you are defining these two attributes. Definition window See Object Definition window. 4 Glossary Demand Limiting A control strategy that monitors and compares power demand over a sliding interval. It then projects average power demand during the interval and temporarily turns Off selected equipment to avoid exceeding predetermined demand peak targets. Dial-Up I/O A software feature that provides automatic phone connections between NCUs and remotely located Operator Workstations and printers. Differential An optional software setting to reduce excessive alarm and warning reports, caused by fluctuations above and below set limits. Digital Control Module (DCM) A point interface and control module that resides in either the NCU or NEU. It functions as a co-processor for the NCM, providing Proportional Integral Derivative (PID) algorithms to independently regulate modulating devices. The DCM is equipped with universal inputs and universal outputs. Directory Manager A software program that facilitates information flow throughout the network. It helps the software find attribute data quickly so information can be passed on to other controllers and operator devices. Disable A command that stops an object from triggering control processes, sending COS messages to operator devices, and accepting commands (except for Enable). download Passing of a program and data bases from an operator device to a NCU. DOS Disk Operating System. Dynamic Data Access (DDA) The communications concept designed by Johnson Controls Inc., that allows the Metasys Network to communicate with every component on an equal basis with complete freedom of information transfer. Dynamic Data Exchange(DDE) A message passing protocol defined by Microsoft Corporation as a Windows standard that allows the exchange of information between two independent Windows applications. Enable A command that resets the Disable command and allows the object to trigger control processes, send COS reports to operator devices, and accept other commands. Engineering Units An operator-defined analog unit (such as DEGF or CFM) that has been defined by the user to be associated with a specific value. Glossary 5 Ethernet Router A Metasys component that integrates Metasys N1 LAN segments with an Ethernet network that uses the TCP/IP protocol. The router provides the physical connection between the Metasys ARCNET segment and the Ethernet network. Facility Management System (FMS) A combined network system of Operator Workstations, Network Control Units, Network Expansion Units, Application Specific Controllers, Network Terminals, and points used to control and monitor a building or group of buildings. Feature A software program that uses data from objects to perform building control operations (i.e., Totalization, Demand Limiting, or Point History). fiber optic active link A device that is used for media conversion between coax and optical fiber. file See record. Fire Controller object The hardware object that defines the interface between the IFC-1010 or IFC-2020 Fire Alarm Controller and the Fire NCM. Fire Management A software set in the NCM that provides Metasys control over the IFC-1010 or IFC-2020 Fire Controller. FM See Function Module. FMS See Facility Management System. Focus window A detailed summary that contains attributes for a specific object. See also Object Focus window. Function Keys Special keys on an I/O device that can perform frequently used functions with a single keystroke. Function Module (FM) A sensor/controller conditioning device that interfaces a field device to a DCM and in some cases an XM. Gateway See JC/85 Gateway. Global Data Sharing Generally used to describe a method of defining current point data values as accessible to other devices. The Dynamic Data Access feature in Metasys goes beyond Global Data Sharing by making all values and all attributes from all network objects accessible throughout the network. 6 Glossary GPL See Graphic Programming Language. Graphic Programming Language (GPL) A symbol-based language used to define control strategies and object data bases for a Metasys Network. Group Name One of the three hierarchical name levels for objects used to assist the user with grouping objects within summaries more clearly at an Operator Workstation. The other hierarchical name levels for objects are Network Name and System Name. Hand-Off-Auto (HOA) A manual hardware override switch located on the XRL Point Multiplex Module and some Function Modules. The HOA switch either places the contacts into the same position as if the relays were turned On (H), if the relays were turned Off (O), or places the relays under automatic (A) control. Hardware Object Manager A software program that transmits data from the NCM to the N2 or L2 Bus. hardware object record A record that contains information on the physical location of an object within the network. hardware objects The name of the software definition for an operator device, printer, or a controller. high voltage A voltage value equal to or greater than 480 VAC. HOA See Hand-Off-Auto. HVAC PRO The standard Metasys software tool for creating control strategies for Application Specific Controllers. IAC-600 Intelligent Access Control System The system that automatically controls access to a facility by the use of access cards (badges). The IAC-600 System is comprised of a D600 Controller, up to 16 Smart Terminal Interfaces (STIs) and card readers, and up to 128 binary input alarm points. IAP Function Module See Input Analog Pneumatic Function Module. IBF Function Module See Input Binary Frequency Function Module. IBN Function Module See Input Binary Function Module. Glossary 7 IDP Function Module See Input Differential Pressure Function Module. IFC-1010 Controller A 2 loop, 198 device intelligent analog addressable fire alarm system that performs fire management functions within Metasys. IFC-2020 Controller A 10 loop, 1980 device intelligent analog addressable fire alarm system that performs fire management functions within Metasys. ILC See Intelligent Lighting Controller. Input Analog Pneumatic (IAP) Function Module Interfaces incoming field signals to the DCM by converting the pneumatic input pressure signal into a proportional analog signal for use by the DCM (multiple ranges available). Input Binary Frequency (IBF) Function Module Interfaces incoming field signals to the DCM by sensing field data (such as rapidly cycling contact closures or input voltages), and converting the input frequency to a DC voltage for use by the DCM. Input Binary (IBN) Function Module) Interfaces incoming field signals to the DCM by converting field data from two different binary inputs to a DC voltage range for use by the DCM. Input Differential Pressure (IDP) Function Module Interfaces incoming field signals to the DCM by converting differential pressure signals into a proportional analog signal for use by the DCM. Input Universal (IUN) Function Module Interfaces incoming current, voltage or resistance signals to either the DCM or to an XM that is inserted in a DCM slot. Intelligent Lighting Controller (ILC) A programmable ASC that performs On/Off control of building light circuits and other switchable loads. It can operate either as a standalone controller or be integrated into the Metasys Network. IUN Function Module See Input Universal Function Module. JC/85 Gateway A software set providing a special application of the NCM to integrate Metasys object information with the JC/85 CPU. In the Gateway application, the NCM serves as a high-level protocol translator, making Metasys object information available to a JC/85 headend. L2 Bus A local communication network that connects the C210 Application Specific Controller or the C260 Application Specific Controller to an NCM. 8 Glossary Lab and Central Plant (LCP) Controller An Application Specific Controller used for single chiller or boiler plant control applications, or for controlling the HVAC process of a laboratory environment. LAN See Local Area Network. Laptop Computer A portable version of the Operator Workstation. LCP See Lab and Central Plant Controller. line-voltage A voltage value of not less than 42 VAC RMS and not more than 479 VAC. Load Rolling An energy saving feature that temporarily turns Off equipment to meet a specified energy reduction target. Load table Used with the Demand Limiting and Load Rolling features to define which loads have been selected as shed candidates and the priority in which they must be shed. Each load table may have up to four priorities defined. Local Area Network (LAN) A combination of hardware and software that enables Operator Workstations and NCMs to share data base information, hardware resources, and application programs. low-voltage A voltage value of less than 42 VAC RMS. manual commands All available commands entered manually at an Operator Workstation or Network Terminal. mapping objects Corresponding a set of values having defined parameters with the quantities or values of another set. message User-defined ASCII text that can be associated with a COS report. Metalink An optional feature of Metasys that allows the exchange of information between Metasys and independent third-party software applications such as Microsoft Excel. It provides a Microsoft Windows Dynamic Data Exchange (DDE) interface to Metasys. Metastat A family of temperature sensing products designed for use with Application Specific Controllers. Glossary 9 Metasys An evolutionary distributed Facility Management System, designed by Johnson Controls, Inc. Metasys Integrator A type of Network Control Module (NCM200) that allows qualified thirdparty controllers to be connected to the N2 Bus, much like the standard ASCs. The connectivity provides greater flexibility in FMS design, implementation, and system evolution. Migration See S2 Migration. mixed network One of three available configurations for the Metasys N1 LAN. The mixed network configuration consists of a combination of the star and bus network components. Multiplex Binary (XBN) A Point Multiplex Module that monitors up to 32 binary inputs and reports changes in their states to the NCU for processing. Multiplex Relay Electrically Maintained (XRE) A Point Multiplex Module that monitors up to eight binary inputs and executes output commands through eight electrically maintained relays. The XRE also reports input changes-of-state and HOA switch settings to the NCU for processing. Multiplex Relay Latched (XRL) A Point Multiplex Module that monitors up to eight binary inputs and executes output commands through eight magnetically latched relays. The XRL also reports input changes-of-state and HOA switch settings to the NCU for processing. Multiplex Relay Momentary (XRM) A Point Multiplex Module that monitors eight binary inputs and executes output commands through eight momentary relay pairs. The XRM also reports input changes-of-state and Auto/Manual switch settings to the NCU for processing. N1 LAN An ARCNET local area network that interconnects NCUs and Operator Workstations. N2 Bus A local Optomux network that interconnects ASCs, XMs, and NEUs to an NCU. NCM See Network Control Module. NCSETUP A software program, running on a laptop PC or the Operator Workstation, that configures each NCM. 10 Glossary NCU See Network Control Unit. NEU See Network Expansion Unit. Network A collection of Operator Workstations, printers, NTs, NCUs, NEUs, ASCs, N1 LANs, and N2 Buses which make up a FMS. Network Control Module (NCM) The main processing module in the Network Control Unit. Fully programmable, the NCM coordinates and supervises the control activities for all objects and control loops hardwired to the NCU, as well as the remote NEUs and Application Specific Controllers connected to it over a local N2, L2, or S2 Bus. Network Control Unit (NCU) A standalone panel used to control a building’s mechanical equipment. The NCU consists of an enclosure, door, and baseframe to house electronic modules (an NCU must include a Network Control Module), terminal blocks, and signal conditioners. It is highly flexible in hardware and software configuration and provides direct digital control, energy management, supervisory control, and point monitoring. Network Expansion Unit (NEU) A remote field panel to expand the I/O point and control loop capacity of the NCU. The NEU contains the same configurable modules as the NCU, but without the NCU’s user-programmable main processor, the Network Control Module (NCM). Network Manager A software program responsible for dynamically updating the screen with realtime data. Network Map The first screen to appear on an Operator Workstation after logging on. It displays the structure of the recently activated network in true diagram form. Network Name One of the three hierarchical name levels for objects used to assist the user with grouping objects within summaries more clearly at an Operator Workstation. The other hierarchical name levels for objects are System Name and Group Name. Network Port A Metasys component that monitors and controls the Metasys FMS from a third-party computer serving as a host. The Network Port emulates the Allen-Bradley PLC-5 Programmable Logic Controller. Network Terminal (NT) A hand-held operator’s device used to access point data, change operating parameters and schedules, and perform overrides at the NCU. Glossary 11 Network Terminal Emulator An IBM PC, AT, or PS/2 computer, or a Toshiba laptop loaded with NT Emulation software. The NT Emulator can perform the same functions as the Network Terminal. Network Tool Box An optional diagnostic package for the Operator Workstation. Network Transparency A characteristic of the Metasys Network. Network transparency allows the operator to view information about a facility without knowledge of, or restriction from the physical devices in which that information is stored. NEU See Network Expansion Unit. Node Any addressable device connected to the N1 LAN. A node can be a Network Control Module or an Operator Workstation. normalband Defines the width of the normal operating range for objects. NT See Network Terminal. OAE Function Module See Output Analog Electrical Function Module. OAI Function Module See Output Analog Isolated Function Module. OAP Function Module See Output Analog Pneumatic Function Module. OBE Function Module See Output Binary Electrical Function Module. object A software data base record that corresponds to and characterizes a field device, a data point, an N2 address, or a control function. Object Definition window Used to define an object online at an Operator Workstation. Object Focus window Used to view the condition of an existing object and/or modify attributes online at an Operator Workstation. Object Identifier The name identifying a specific object in a system. The Object Identifier is a 2-part name (up to 16 characters in length) consisting of a System Name and an Object Name. Object Manager Software that resides in the NCU and is used to control and characterize objects. 12 Glossary Object Oriented Architecture A software design technique where information about a specific item is stored so that it is readily available to users and application programs. All the attributes of an object are stored at the same place as the object. Operator Workstation A Personal Computer-based operator interface used for sophisticated information management, data storage, and system programming. Optomux Communications protocol used on the N2 Bus. ORE Function Module See Output Relay Electrical Function Module. ORL Function Module See Output Relay Latched Function Module. ORM Function Module See Output Relay Momentary Function Module. OSV Function Module See Output Solenoid Valve Function Module. OTE Function Module See Output Triac Electrical Function Module. Output Analog Electrical (OAE) Function Module Interfaces between the DCM and analog output field devices. It may be configured to source analog output voltage, source analog output current, or modulate current for externally powered devices. Output Analog Isolated (OAI) Function Module Provides an isolated interface between the DCM and analog output field devices. It may be configured to source analog output voltage, source analog output current, or modulate current for externally powered devices. Output Analog Pneumatic (OAP) Function Module Interfaces between the DCM and field devices to provide pneumatic pressure control. Output Binary Electrical (OBE) Function Module Interfaces between the DCM and field devices to provide incremental control of a field device. Output Relay Electrical Maintained (ORE) Function Module Interfaces between the DCM and field devices to provide On/Off control for the field devices via electrically maintained relays. Output Relay Latched (ORL) Function Module Interfaces between the DCM and field devices to provide On/Off control for the field devices via magnetically latched relays. Glossary 13 Output Relay Momentary (ORM) Function Module Interfaces between the DCM and 2-state field devices to provide On/Off control for the field devices via momentary relays. Output Solenoid Valve (OSV) Function Module Interfaces between the DCM and field devices to provide 3-way solenoid air valve control of a pneumatic output signal to field devices. Output Triac Electrical (OTE) Function Module Interfaces between the DCM and field devices to provide increment/decrement control. Override A manual command available at the Operator Workstation or Network Terminal. It allows the operator to define a current value for an output object at a high priority. Override replaces the current value with the userdefined value. Password A global security feature that restricts access to the system from the Operator Workstation or Network Terminal. PID Loop (PIDL) object Used to manipulate outputs for closed-loop control at a given Digital Control Module. The PID Loop object is the software that generates these outputs by using a collection of inputs and other variables to perform calculations and issue commands. PIN (Personal Identification Number) Code A number that must be entered at a card reader keypad in order to gain access to a facility. PMI Person/Machine Interface. Point History A feature that maintains a recent history of the values, actions, object status, and flags associated with each point object. Point Multiplex Module (XM) A family of binary sensor/controller interface devices that reside in the NCU or NEU. See also XBN, XRE, XRL, and XRM. point object Software that corresponds to and characterizes field devices and data points. There are eight types of point objects: Accumulator, Analog Data, Analog Input, Analog Output Digital, Analog Output Setpoint, Binary Data, Binary Input, and Binary Output. Process A self-sufficient, modular block of computer instructions for an NCM. Processes are used to implement control strategies. 14 Glossary Pseudo point Also called Data or Duplicate point. May be a duplicate definition (copy) of an actual physical point or the result of a calculation or logical operation in a control process like GPL. Ranging A function that converts the analog-to-digital counts from the field into data for operator use. Realtime Operating System (RTOS) Johnson Controls multi-tasking operating system. It provides an environment in which several programs can run simultaneously. record Formatted data representation for the Report Router. Repeater An adapter card that extends the length of the N2 Bus beyond 5000 feet, or increases the number of N2 devices beyond 50. report A specialized grouping of displayed points not solicited by the user. Report Router/Alarm Management A central distribution system for messages and files. It displays critical Alarms in custom windows, allowing flexible operator processing of Alarms and reports. RTOS See Realtime Operating System. S2 Migration A software set in the NCM that brings JC/85 field gear, object information, and control directly into Metasys from the JC/85 trunks. sample Each individual polled event (i.e., a snapshot of parameter values). Scheduling A feature that allows the user to schedule commands and summaries individually by the following parameters: time, day of week, and holiday. Optimizes energy use while providing flexible scheduling for individual and system variations. Security Key A module that plugs into the parallel port of the Operator Workstation. It is required to run Metasys PMI software and protect from illegal use and copying of the software. segment For the N1 LAN, an electrically continuous section of cable that is terminated at both ends (i.e., does not pass through an active hub or active link). For the N2 Bus, an electrically continuous daisy-chained cable between repeaters or repeaters to end-of-line. Glossary 15 Self-Tuning PID Control A software feature that automatically and continually modifies (fine-tunes) PID Loop parameters to maintain a correct output value. Smart Terminal Interface (STI) One of up to 16 terminals linked to the D600 Controller in an IAC-600 Access Control system. An STI controls card reader and door security hardware, and monitors a group of local binary input alarms. Its associated card reader reads access cards. Software Model A predefined set of attributes used as a default for defining Control System (CS) software objects. Software Object Manager A software program that obtains information from object records in order to perform building control operations. Software Object Record A software record that contains attribute data pertaining to the operation of the object. Staff Workstation A Metasys software option that serves as a complete Metalink application. It provides users with simple and convenient access to temperatures, humidities, and setpoints. The source code of the application is provided and can be customized by the applications engineer. standalone The ability of a controller to perform a defined set of functions without supervisory control on any other device. star network One of three available configurations for the Metasys N1 LAN. The star network configuration consists of two or more nodes connected to a multiport repeater called an active hub. System Directory Part of the NCM’s Directory Manager. The system directory lists which systems are defined for each specific NCM. System Name One of the three hierarchical name levels for objects used to assist the user with grouping objects within summaries more clearly at an Operator Workstation. The other hierarchical name levels for objects are Network Name and Group Name. System/Object Name See Object Identifier. TBC See Communication Terminal Board. Time Manager A software program that keeps track of the time of day, day of week, date, holiday, and alternate or regular schedules. 16 Glossary Time-Out An action performed by the Operator Workstation and Network Terminal that automatically logs off the screen if the keyboard isn’t used within a user-specified period of time. Time Scheduling See Scheduling. Token A unique combination of software bits that grant a specific node on the N1 LAN permission to transmit. Token bus A Local Area Network (LAN) that features a layout in which the nodes are wired in a daisy chain. It uses a 2-port repeater called an active link for expansion. Token passing A local network access mechanism in which a token is passed from node to node in sequential order; nodes must wait for the token to arrive for access to the network to transmit data. Totalization Feature for counting the number of occurrences of particular events or accumulating totals of the quantity of a particular commodity as it is used, processed, or encountered. There are four types of Totalization: analog, runtime, pulse, and event. Trend A user-defined monitoring feature which gathers the data needed to review the performance of an entire building or of an individual piece of equipment. Triggerable The capability of being triggered; applies to an attribute that can cause (trigger) another operation to occur. For example, if an analog input temperature sensor goes into high Alarm, it can cause a binary output to start a supply fan. Unitary Controller (UNT) An Application Specific Controller used for digital control of package air handling units, unit ventilators, fan coils, heat pumps, and other terminal units serving a single zone or room. Upload/Download Exchanges data between the NCM and Operator Workstation. This process may be automatic (in the case of a NCM request following power loss), or it may be a manual request from the user (through the Operator Workstation). User Programs Executes calculations, sequences of operation, control logic, interlocks, and other supervisory control programs written in GPL. Glossary 17 Variable Air Volume (VAV) Controller An Application Specific Controller used for digital control of single duct, dual duct, fan powered, and supply/exhaust VAV box applications. Warm Start Restarting the Network Control Module so that remains fully operational following initial diagnostic tests. When the Network Control Module is warm started, both code and data remain safely stored within Dynamic Random-Access Memory (DRAM). Contrast with cold start. writable The capability of being written to; applies to attributes the operator may modify (or write to). XM See Point Multiplex Module (XM). XBN Point Multiplex Module See Multiplex Binary (XBN). XRE Point Multiplex Module See Multiplex Relay Electrically Maintained (XRE). XRL Point Multiplex Module See Multiplex Relay Latched (XRL). XRM Point Multiplex Module See Multiplex Relay Momentary (XRM). Zone object A software object that represents one IFC-2020 fire zone residing in an IFC-2020 Fire Alarm Controller. Zone Terminal (ZT) A hand-held or wall-mounted device that is used to monitor and adjust your HVAC system within a specific building zone. ZT See Zone Terminal. 18 Glossary Notes Glossary 19 Notes Controls Group 507 E. Michigan Street P.O. Box 423 Milwaukee, WI 53201 20 Glossary FAN 636 Metasys Network Technical Manual Release 4 Printed in U.S.A.
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