Building Automation Knowledge Base

Issue The properties of any server, Enterprise Server or Automation Server, in SmartStruxure has a Communication tab that will list the IP addresses of all associated servers on the network. Changing the IP address of an AS requires every other AS to know about the change in order to preserve any server-to-server communication. In the example below, the system has been engineered in-house on a 10.10.x.x network domain. It was then moved to site where the domain of the ES and all AS were changed to 10.159.x.x. Viewing the Communication tab on the ES shows all IP addresses have been properly updated: However, if the DNS/IP Address column is viewed from the Communications tab of one of the Automation Servers, the results vary as to which IPs have been properly updated: Automation Server A Automation Server B Automation Server C If there is any communication between two Automation Servers, and the IP addresses have not properly updated, then communication between them will break. Product Line EcoStruxure Building Operation Environment Building Operation Enterprise Server Building Operation Enterprise Central Building Operation Automation Server Building Operation Automation Server Premium Building Operation Automation Server Bundled Building Operation Edge Server - Standard Cause Any change to an Automation Server's IP address must be represented in the Enterprise Server (if there is one). It must also be updated in all associated Automation Servers. It is best practice following the change of any IP address on the system to perform a refresh of the addresses from the Enterprise Server. Note: This is also applicable in a network with Enterprise Central hosting Enterprise Servers. Resolution Right Click on the ES. Select Advanced>Repair Server Communication. Refer to: Repairing EcoStruxure BMS Server Communication

Issue I/A Series G3 Modbus TCP communications to random Modbus devices randomly drop offline and stop communicating with the ENC or Enterprise Network Server.  Both the modbusCore and modbusTcp modules are at version 3.6.31. Product Line TAC IA Series Environment I/A Series G3, Modbus TCP 3.6.47 and lower Cause There were a few updates to the Modbus core and TCP modules between 3.6.31 and 3.6.47. Issue 18656 corrected communication reliability when there are a large number of Modbus TCP devices under a single ModbusTcpNetwork. Issue 19897 corrected transaction ID synchronization when a retry occurred. Issue 23578 added the ability to control the maximum transactionID used for ModbusTcp (I/A Series G3 Modbus TCP communications to Siemens Moore 353 controller stops updating after a period of time after ENC/JACE reboot or station start). Resolution Download the following modules from The Exchange Download Center: modbusCore-3.6.47.1.zip modbusTcp-3.6.47.1.zip Install to the appropriate I/A Series G3 Workbench modules folder Upgrade the modules in the ENC/JACE.

Issue Unable to access ES or AS after setting a new Domain as the default domain Product Line EcoStruxure Building Operation Environment Building Operation Enterprise Server Building Operation Automation Server Premium (AS-P) Cause If you set a domain as a default domain before logging in through that domain, it is possible that you do not have users set up and therefore will be locked out of the system. Resolution Open Building Operation Workstation Enter a Username and password for the Local domain or another previously functional domain Set the Domain as "Local", please note that this is case sensitive. Select the correct Server Log in Change the default domain back to Local until you have successfully logged in using the new domain.

Issue Vista webstation - Error message in FIPS-compliant systems first time the logging screen is entered and red X instead of values in TGML pictures Error message in FIPS-compliant systems when Windows Communication Foundation is used to serialize generic types: “This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms” Red X instead of values EcoStruxure Building Operation registration WorkStation Error Product Line TAC Vista, EcoStruxure Building Operation Environment Vista Webstation Cause System cryptography: Use FIPS compliant algorithms for encryption, hashing and signing This security setting determines if the Transport Layer Security/Secure Sockets Layer (TL/SS) Security Provider supports only the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher suite. In effect, this means that the provider only supports the Transport Layer Security (TLS) protocol as a client and as a server (if applicable). It uses only the Triple DES encryption algorithm for the TLS traffic encryption, only the Rivest, Shamir, and Adleman (RSA) public key algorithm for the TLS key exchange and authentication, and only the Secure Hashing Algorithm 1 (SHA-1) for the TLS hashing requirements. For Encrypting File System Service (EFS), it supports only the Triple Data Encryption Standard (DES) encryption algorithm for encrypting file data supported by the NTFS file system. By default, EFS uses the Advanced Encryption Standard (AES) algorithm with a 256-bit key in the Windows Server 2003 family and DESX algorithm in Windows XP for encrypting file data. For information about EFS, see Encrypting File System. NOTE - The same errors can occur in EcoStruxure Building Operation when registering. Resolution Go to Local Security Settings Security Settings > Local Policies > Security Options System cryptography: Use FIPS compliant algorithms for encryption, hashing and signing = Make sure its disabled to get to local security you can go to 1. go to start 2. Go to run 3. enter secpol.msc 4. press enter NOTE - The same errors can occur in EcoStruxure Building Operation when registering. The Resolution is the same

Issue Notifications (email or text file) are sent when an alarm is enabled by the shunt variable Environment Notifications Cause The Alarm object has 6 possible states that it can take   Normal - Idle state where the alarm monitors the variable. Alarm - When an alarm is triggered, the state of the alarm changes from the normal state to alarm state. Disabled - You can disable an alarm when the alarm is triggered by faulty reasons, the alarm toggles between the alarm state and reset state, or maintenance will trigger the alarm. A Disabled alarm can be hidden in the Alarms pane or Alarm Views. To reset the alarm, you have to show hidden alarms and then enable it. When you show disabled alarms, enabled alarms are hidden. Alarms are also disabled by using the Shunt Variable in the alarm configuration. Reset - The monitored variable has returned to a value that is within the normal condition of the alarm, but the alarm has to be acknowledged by a user before the alarm returns to normal state. Acknowledged - A user or user group has acknowledged the alarm. Fault - If a BACnet device reports values that it knows are not trustworthy, the monitoring alarm is put in fault state. The notification is triggered by transitioning to any of these states as selected in the "Notify on transition to" portion of the notification configuration This means that if you wish to receive a notification on transition to the Normal state, you can check the Normal box. However, this means that not only are notified when the alarm transitions from Alarm to Normal, but from Disabled to Normal or Fault to Normal.  Some of the scenarios may be undesirable. Resolution There are two ways an alarm can go to Normal: Alarm to normal Disable to normal In the Email notification main filter, you can choose to not get a notification from disarm but you might want to get a email about normal since you want to get a email when an alarm goes to normal. To accomplish this you need to add another filter called "Previous alarm state." (This filter does not work in releases prior to 1.3 SP1.) To add the filter Previous Alarm State: Click on the green + Check the boxes you want: Acknowledge Alarm Normal Reset Make sure Disable is not checked This means that when the previous state was disabled (shunted), a notification will not be sent.   Example1: This object will always trigger a notification on Alarm.  The notification will be triggered regardless of Previous State. If the Alarm is Disabled by a shunt, then enabled, but the Monitored Variable is still out of Range, a notification will be sent.   Example2: This object will only trigger a notification on the Transitions from Alarm to Reset, Alarm to Normal, Acknowledged to Reset or Acknowledged to Normal. This might be desirable for a user that wished to know when an object in Alarm returns to normal operation, but not know when an alarm goes from Disabled to normal operation.

Issue There are many BCX1 on the site. All of the BCX1s go offline when reloading the controller. Environment BCX1-CR B3 Continuum Cause Checking the system configuration and programming. The reasons listed below may cause significant traffic on the network. A lot of Polling value of points across controllers COV increment is set to zero Check all the numeric points' setpoint attribute including Runtime, DamperPosition, etc. as these change all the time. Points under b3 controllers are referenced by more than 32 devices. Device in the BACnet Device folder doesn't match the controller in infinity side.(Not deleted device from BACnet folder after replace the controller) When the special trunk with low quality cable  connect to BLink also cause this issue. Remove the problem trunk, the issue will be  gone When the heavy traffic happens on the network or some other issues , it will cause unexpected issues. Resolution Change the programs way, create a program in the BCX1 to mirror the referenced points in b3s Uncheck the setpoint attribute of all numerics except  temperature setpoint. Change the polling program flow type from looping to fall thru and trigger every minute or trigger by other digital point. Set the COV increments to a non-zero value After device replacement, delete the device from BACnet Device folder and find new BACnet device again, then send to database Remove the problem trunk from Blink or try to change the terminal resistor will  resolve this issue  After the steps above are done, the network should be stable and the BCX1 will no longer go offline when reloading.

Issue Rehosting is defined as the process of moving a license from one machine to another. Is there a limit to the number of rehosts allowed per year? Product Line EcoStruxure Building Operation,TAC Vista Environment Building Operation Licensing Cause Re-hosting means that the license bindings to the physical hardware or its substitutes on a Virtual Machine are moved i.e. the host ID is changed. This can be required if the license is moved to a new computer or Virtual Machine.  A maximum of 4 license re-hosts are allowed in 12 months. Resolution If the re-hosting limit is exceeded and further re-hosting is justified and necessary, the policy can be overridden by Product Support. When contacting support please provide the entitlement details so that the license policy can be overridden.

Issue Valid Users are randomly unable to gain access when presenting at a Suprema biometric reader. Sometimes they are able to gain access but others they are not and see user denied events in the events window. User denied entry by entry mode error door mode is not correctly programmed using invalid reading device User Denied Event Product Line EcoStruxure Security Expert Environment Security Expert Suprema BioEntry W2 fingerprint reader Cause The sensitivity settings in the Suprema software are too sensitive resulting in missed fingerprint reads. Resolution Reducing the fingerprint sensitivity from the default setting of 7 to a setting of 5 may allow fingerprints to be read more reliably.   The sequence used to authenticate the User can also result in more frequent read failures. Presenting a valid card then an invalid (or bad read) fingerprint and then presenting the card again,  the sequence starts all over again and will result in a user denied event. If the user presents the correct finger (after presenting the wrong finger) or tries the same finger again within the configured timeframe they will be granted access.

Issue How to configure a LON router in Niagara R2. Environment Niagara R2 LON Cause Troubleshooting Resolution Review / download documentation here.

Issue I/A Series G3 HTML navigation tree example   Environment I/A Series G3 graphics Cause Need an example of creating a HTML navigation tree for I/A Series G3 graphic pages. Resolution The demo station that is installed with the I/A Series G3 software includes an example of a HTML navigation tree. Open the demo station in Workbench and go to Config > Services > UserService. Open up the user 'adminFrames'. From here you can see that the Web Profile used is the Handheld Wb Web Profile. The Nav File used is 'frames.nav'. In the station, go to Files and then the nav folder. Expand the folder and open the 'frames.nav' nav file. From here, we can see that the target ord for the home page is frames/home.html.  In Windows Explorer, navigate to \niagara\niagara-3.x.xxx\stations\demo\frames. You can see 3 files here, home.html, top.html and tree.html. Look at these 3 files to see how the tree and frames are created. The images folder contains the images used on the page.  Major steps. Engineer your station database and graphics as what you would do normally.  Create user(s) that uses the Handheld Wb Web Profile.  Create a nav file that points to home.html. Assign the nav file created in step 2 to user(s) created in step 1. Edit the home.html, top.html and tree.html according to your requirements.  User(s) created in step 2 will have the tree view when they log on from a web browser. 

Issue What files are saved, to where and why is this used. Product Line EcoStruxure Building Expert Environment SmartStruxure Lite Multi-Purpose Manager (MPM) All variants: VA, UN, GW Cause The running database of a SmartStruxure Lite MPM controller is in the controllers volatile memory (RAM), in order for this data to be preserved during a power failure or reboot this needs to be saved to non volatile memory (Flash) Resolution The save period is for backing up the controller database to flash memory, this can be set to Never, Hourly or Daily. All programming and runtime information is then saved to the controllers flash memory so that it is not lost during a power failure or controller reset. Stored data includes Controller status, configuration changes, updates such as trended information or setpoint changes, and Lua scripts.

Issue Cannot communicate with an EF1 electricity meter. Environment Modbus Electricity Meter EF1 Cause Cannot communicate with an EF1 electricity meter using Modbus. Resolution The settings need to be as follows; IC-Modbus Communication settings; Modbus RTU 9600 baud 8 Data bits Even parity 1 stop bit Fit a 120 ohm resistor across the RS 485 connections Gateway.txt entry - Point number,9,4,0,1,0x1102,0,0,0 Meter Wiring U+ - Power supply can use 7 - 24 volts dc, but tested using 12v - 15v. B connection to IC3-Modbus Terminal C2 A connection to IC3-Modbus Terminal C1 GND - Power supply 0v To review the EF1 data sheet please click HERE. To download the Windmill ComDebug software, please click HERE, or to get the latest version, register at http://www.windmill.co.uk and download from there.  

Issue Webstation closes by itself Environment Webstation  Internet Explorer 9 32bit Cause Vista webstation and TGML do have some compatibility issues with Internet Explorer 32 bit that can cause the webstation to log out itself or even close down when login in. Also a Internet Explorer 32 bit needs to have Java 32 bit installed. On a 64 bit machine if you want to run 32 bit make sure the Java 32 bit client is installed. A normal error to see when those happen is:  --- A fatal error has been detected by the Java Runtime Environment: EXCEPTION_ACCESS_VIOLATION (0xc0000005) --- Resolution Following workarounds have been confirmed to help.  Enable the compatibility view in Internet Explorer 9 Upgrade to Internet Explorer 10  Make sure you have Java 32 bit installed.  Use Internet Explorer 64 bit

Issue Even though the curve block is set to range between 0-100, the block just stays at a fixed output somewhere in the curve output range. Product Line TAC Vista Environment Vista Workstation Cause The curve requires the first entry of the X value to be the lowest value, and then the subsequent values to be larger than the previous X entry. Resolution Adjust the order of the XY entries on the curve block so the first entry in the X will be the lowest value. Example of Incorrect Curve Here is an example of a Curve that will not work. Note the first X entry is -2 and the last X entry is -6.  Example of Correct Curve To correct this curve, -6 is the lower number, so this should be the first X entry. Here is an example of the curve that has the correct X entry order.

Issue When opening I/NET on a secondary monitor, and open the point control window of I/NET summary for a digital output, the drop list for the point doesn't work. Nothing is shown in the drop list. Product Line EcoStruxure Building Operation,TAC INET Environment I/NET SmartStruxure Cause There is a 3rd party system dll file out of date for I/NET. Resolution There is a 3rd party system dll file under the folder C:\Program Files\INET Seven\Program Files (Program Files (x86)) if for a 64 bit Operation System called SftBx32.dll. Click here to download the new dll file and extract it. Close I/NET IO Server and SmartStruxure Enterprise Server Copy this new dll file and replace the old one under that path. Start I/NET and SmartStruxure again, and it should work now.

Issue CNT block in the Function Block Editor is replaced by the PI block. How to set up a pulse counter input in a function block program Environment StruxureWare Building Operation Workstation Function block editor Cause Differences between the regular Menta and the Builder Function Block editor programming Resolution The CNT block is replaced by the PI (Pulse input) block in the function block editor. In Workstation, connect the PI to a input where the sensor type is set to counter.

Issue When evaluating Inet Transition sites, a common error seen when uploading I/NET controllers under the  Inet Interface is an upload failure.  The Background Status and trace log will contain a changeset error as shown below: UploadDevice failed to process changeset on link: 93 station: 10, type index: 17 cannot continue upload Product Line EcoStruxure Building Operation, TAC INET Environment Ecostruxure Building Operation Inet Interface  Cause Understanding the ChangeSet Indices used by the developers will help pinpoint where the issue is originating from.  The message typically isolates the Link and Station but does not identify where within this controller the problem may lie.  Resolution The current list of ChangeSet Indices are listed below and attached Changeset_index.txt Index Affected 9 DCU passwords, States, Eng units, Conversion Coeff., Controls, Holidays, DDC history, Override access, Sunrise/Sunset 11 Points 15 Action message, DCU DDC, Event sequences 17 Calculation 19 Event extension 21 Extension general (can be one of: Runtime, Consumption, or Alarm inhibit - depends on DCU type) 23 ATS 25 ATC 27 Extension application (can be one of: Demand, ORB, ORBEM, UC, LZ, LC, Elevator - depends on DCU type) 29 Trend 31 Lookup table (raw data) 33 Demand load (raw data) 35 MCU 37 MR DDC 39 AIC sequence (raw data) 43 LCD page, Istat param, IAS (raw data) 45 Access control (raw data) Note: "raw data" indicates user cannot manipulate in EBO but it is uploaded and save in raw form to allow for a download/restore Working with the example shown in the Issue, the message indicates a changeset value of Index: 17.  Using the attached list, Index 17 indicates that the issue is within the Calculation Editor. Using the SAV file from the site and working offline within I/NET open this SAV file and check each of the editors, in this case, calculations. In most cases, it will either be an invalid character or invalid point address - which will be shown as 'blank' as seen below: Correcting this and updating the SAV file to the controller (Station Restore) will typically correct this issue. If the same error persists then please provide an Export of the Inet Interface and the SAV files of the controllers having this problem through your local support channel.   

Issue The SE8000 documentation states that the power supply voltage is 7 Volts DC but the circuit board sticker says 7 VDC/24 VAC. Can the controller be powered from 24 VAC? Product Line EcoStruxure Building Operation, EcoStruxure Building Expert Environment Building Operation Workstation Building Operation Automation Server SSL SE8000 Cause An incompatible relay pack might have been used. Resolution Typically the SER8300 range are intended to have power supplied by the SC3000 relay pack which supplies the 7VDC. If an SC3000 relay pack is not used, for example, if the SER8300 is just being used as a wireless device then it is acceptable to power it from 24VAC.

Issue How can an Airlock door system be implement in Continuum? Product Line Andover Continuum Environment Continuum Cyberstation Continuum Net Controller II Continuum ACX 2 Controller Continuum ACX 4 Controller Cause Sample PE program is needed as a general guideline on how to implement an Airlock control system in Continuum. Resolution The use case and implementation details are documented in the comment section of the PE program.   Here is the actual PE code to implement, please note that this PE program is provided as a sample only, to serve as guidelines and proof of concept, considerable changes may be necessary to make the program adequate for your particular application and site.    Numeric Green Numeric Red Numeric StrikeTimer Line INIT Green = Unlocked Red = Locked 'LOCK ALL 3 DOORS PerimDrStriker = Locked IntDr1Striker = Locked IntDr2Striker = Locked 'MAKE ALL DOORS AVAILABLE FOR ACCESS TO THE AIRLOCK PerimeterDoor = Green InteriorDoor1 = Green InteriorDoor2 = Green 'ALLOW CREDENTIAL ACCESS PerimeterDoor DisRdrKpAccess = False InteriorDoor1 DisRdrKpAccess = False InteriorDoor2 DisRdrKpAccess = False 'ALLOW EXIT REQUESTS PerimeterDoor OpenOnExitReqst = True InteriorDoor1 OpenOnExitReqst = True InteriorDoor2 OpenOnExitReqst = True Goto Monitor1 Line Monitor1 If PerimeterDoor ValidAttempt or PerimeterDoor ExitRequest then 'ACCESS ATTEMPT AT PERIMETER DOOR StrikeTimer = PerimeterDoor DoorStrikeTime 'UNLOCK THE DOOR... Goto PerimActive 'AND MAKE THE PERIMETER DOOR ACTIVE Endif If InteriorDoor1 ValidAttempt or InteriorDoor1 ExitRequest then 'ACCESS ATTEMPT AT INTERIOR DOOR1 StrikeTimer = InteriorDoor1 DoorStrikeTime 'UNLOCK THE DOOR... Goto Interior1Active 'AND MAKE THE INTERIOR DOOR1 ACTIVE Endif If InteriorDoor2 ValidAttempt or InteriorDoor2 ExitRequest then 'ACCESS ATTEMPT AT INTERIOR DOOR2 StrikeTimer = InteriorDoor2 DoorStrikeTime 'UNLOCK THE DOOR... Goto Interior2Active 'AND MAKE THE INTERIOR DOOR2 ACTIVE Endif 'CHECK FOR FORCED ENTRY If PerimeterDoor DoorSwitch = Opened or InteriorDoor1 DoorSwitch = Opened or InteriorDoor2 DoorSwitch = Opened then Goto AirLockForced Line AirLockForced 'MUST HANDLE FORCED ENTRY HERE DUE TO VALUE OF DOOR BEING SET TO UNLOCK TO MAKE LED GREEN AirLockAlarm = 1 'SEND THE ALARM 'MAKE ALL DOORS UNAVAILABLE PerimeterDoor = Red InteriorDoor1 = Red InteriorDoor2 = Red If PerimeterDoor DoorSwitch = Closed and InteriorDoor1 DoorSwitch = Closed and InteriorDoor2 DoorSwitch = Closed then 'FORCED ENTRY CLEAR, RESET THE AIRLOCK AirLockAlarm = 0 Goto INIT Endif Line PerimActive 'ACCESS REQUESTED AT PERIMETER DOOR, DISABLE CREDENTIAL AND REX ACCESS AT THE INTERIOR DOORS InteriorDoor1 DisRdrKpAccess = True 'DONT ALLOW CREDENTIAL ACCESS AT THE INTERIOR DOORS InteriorDoor2 DisRdrKpAccess = True InteriorDoor1 OpenOnExitReqst = False 'DONT EXIT REQUESTS AT THE INTERIOR DOORS InteriorDoor2 OpenOnExitReqst = False InteriorDoor1 = Red InteriorDoor2 = Red 'UNLOCK THE PERIMETER DOOR PerimDrStriker = PerimeterDoor DoorStrikeTime 'WAIT FOR PERSON TO PHYSICALLY OPEN THE DOOR If PerimeterDoor DoorSwitch = Opened then Goto PerimInactive 'DOOR NEVER OPENED, RESET AIRLOCK If TS > PerimeterDoor DoorStrikeTime then Goto INIT Line PerimInactive 'HANDLE ACCESS REQUEST WHILE DOOR OPENED, EXTENDED DOOR UNLOCK TIME If PerimeterDoor ValidAttempt or PerimeterDoor ExitRequest then PerimDrStriker = (PerimDrStriker + 1) If PerimeterDoor DoorSwitch = Closed then Goto INIT 'WE'VE BEEN HERE TOO LONG, SEND ALARM If TM > 0 then AirLockAlarm = 2 Line Interior1Active 'ACCESS REQUESTED AT INTERIOR DOOR1, DISABLE CREDENTIAL AND REX ACCESS AT THE PERIMETER DOOR PerimeterDoor DisRdrKpAccess = True PerimeterDoor OpenOnExitReqst = False PerimeterDoor = Red InteriorDoor2 = Green 'UNLOCK THE INTERIOR DOOR1 IntDr1Striker = InteriorDoor1 DoorStrikeTime 'WAIT FOR PERSON TO PHYSICALLY OPEN THE DOOR If InteriorDoor1 DoorSwitch = Opened then Goto Interior1Inactiv 'DOOR NEVER OPENED, RESET AIRLOCK If TS > InteriorDoor1 DoorStrikeTime then Goto INIT Line Interior1Inactiv 'HANDLE ACCESS REQUEST WHILE DOOR OPENED, EXTENDED DOOR UNLOCK TIME If InteriorDoor1 ValidAttempt or InteriorDoor1 ExitRequest then IntDr1Striker = (IntDr1Striker + 1) If InteriorDoor1 DoorSwitch = Closed then Goto INIT 'WE'VE BEEN HERE TOO LONG, SEND ALARM If TM > 0 then AirLockAlarm = 3 Line Interior2Active 'ACCESS REQUESTED AT INTERIOR DOOR2, DISABLE CREDENTIAL AND REX ACCESS AT THE PERIMETER DOOR PerimeterDoor DisRdrKpAccess = True PerimeterDoor OpenOnExitReqst = False PerimeterDoor = Red InteriorDoor1 = Green 'UNLOCK THE INTERIOR DOOR2 IntDr2Striker = InteriorDoor2 DoorStrikeTime 'WAIT FOR PERSON TO PHYSICALLY OPEN THE DOOR If InteriorDoor2 DoorSwitch = Opened then Goto Interior2Inactiv 'DOOR NEVER OPENED, RESET AIRLOCK If TS > InteriorDoor2 DoorStrikeTime then Goto INIT Line Interior2Inactiv 'HANDLE ACCESS REQUEST WHILE DOOR OPENED, EXTENDED DOOR UNLOCK TIME If InteriorDoor2 ValidAttempt or InteriorDoor2 ExitRequest then IntDr2Striker = (IntDr2Striker + 1) If InteriorDoor2 DoorSwitch = Closed then Goto INIT 'WE'VE BEEN HERE TOO LONG, SEND ALARM If TM > 0 then AirLockAlarm = 4 Line E If TS > 30 then Goto INIT    See also attached dump file of program code.  

Issue Does Building Operation use Unicast or Multicast? Product Line EcoStruxure Building Operation Environment Building Operation Enterprise Server Building Operation Automation Server Building Operation Workstation Cause Does Building Operation use Unicast or Multicast? Definitions: Unicast packets are sent from host to host. The communication is from a single host to another single host. There is one device transmitting a message destined for one receiver. Multicast is a protocol for use with IP. Multicast enables a single device to communicate with a specific set of hosts, not defined by any standard IP address and mask combination. This allows for communication that resembles a conference call. Anyone from anywhere can join the conference, and everyone at the conference hears what the speaker has to say. The speaker's message is not broadcasted everywhere, but only to those in the conference call itself. A special set of addresses is used for multicast communication. Broadcast is when a single device is transmitting a message to all other devices in a given address range. This broadcast could reach all hosts on the subnet, all subnets, or all hosts on all subnets. Broadcast packets have the host (and/or subnet) portion of the address set to all ones. By design, most modern routers will block IP broadcast traffic and restrict it to the local subnet. Resolution Building Operation is using only IPv4 and therefore Unicast only. This may change when Building Operation begins using IPv6. At that time, a site may want to use the IPv6 multicast features to address groups of targets.