Building Automation Knowledge Base

Issue When the remote I/O modules (MNB-1000-15) are powered for the first time, the status LED stays blinking red. Product Line TAC IA Series Environment I/A Series MNB 1000 -15 Cause This is a normal operation. Resolution When the associated MNB-1000 receives a database configured with remote I/O modules, it will initiate communication with the remote I/O modules. If it is successful, then the status LED with turn green.

Issue Following an attempt to update firmware, some MNB MS/TP controllers appear to be in a locked-up condition (ie: the status LED is red and blinking). Product Line TAC IA Series Environment I/A Series MNB controllers Cause The device was interrupted before completing the update, which cause the controller to be in bootloader mode. Resolution To perform a successful firmware update it is imperative that once the update has been initiated it must not be interrupted until complete. A successful firmware upgrade must be completed to get the controller out of bootloader mode. However, in most cases when this issue occurs the unit is no longer displayed in the WorkPlace Commissioning Tool device list.  Therefore it cannot be selected for an upgrade. To get the unit to show up in the list, it must be added as an MS/TP slave. This is done under the WorkPlace Commissioning Tool menu selection: File – add MS/TP Slave. The network number and the controller's MS/TP physical address must be known. Once defined as a slave it will appear in the list and can be selected for a firmware upgrade. Note: If a controller shows up in MS/TP slave mode and indicates it contains the latest firmware it will be necessary to downgrade it to the previous firmware version to recover the unit and then upgrade to the latest firmware.  To downgrade the firmware in an MSTP device open its Device Properties, go to the Firmware tab and click on "Update firmware".  On the Update Firmware window check the box next to "Check here to preview or modify the updates to be applied and click "next".  On the Update Details window click on the change button and a window with available firmware versions for that controller will be displayed.  Select the "bin" file for the previous firmware revision and click on the Open button.  Now click on the Start Update button to perform the firmware downgrade.  If successful the controller will show up in the WPCT device list and can be upgraded to the latest firmware. If suspect communications are what caused the update failure, it must be remedied prior to attempting another update. Once a successful firmware update has been completed the unit will boot normally.  The status LED will be green and it will appear in the Device list.

Issue The MNB-70 firmware upgrade displays version v1.130 during the upgrade process when upgrading to v1.430   The firmware included with WorkPlace Tech 5.8.5 will display the correct filename (MNBU70-01430.bin) however the version will indicate v1.130 within the WorkPlace Tech Commissioning Tool. The firmware included with the MNB Series v1.430 Firmware Pack extractor will display an incorrect filename (MNBU70-01130.bin) as well as indicate v1.130 within the WorkPlace Tech Commissioning Tool. Product Line TAC IA Series Environment I/A Series MNB 70 I/A Series WorkPlace Tech 5.8.5 I/A MNB Series v1.430 Firmware Pack extractor Cause An incorrect version of firmware for the I/A Series MNB-70 controller has been included with the WorkPlace Tech 5.8.5 distribution and the MNB Series v1.430 Firmware Pack extractor both released in mid-July 2013. Resolution Replace the existing MNB-70 firmware file with an updated version: Locate and delete the existing MNB-70 firmware files (where applicable): MNBU70-01130.bin MNBU70-01430.bin The firmware files are typically located … Windows XP \Documents and Settings\All Users\Application Data\WorkPlace Tech\Firmware Windows 7 \Program Data\WorkPlace Tech\Firmware Download the updated MNB Series v1.430.A Firmware Pack extractor from The Exchange Download Center: MNB Series v1.430.A Firmware Pack - BTL Compliant.exe Execute the extractor and the files will be extracted to the firmware directory for use with the WorkPlace Tech Commissioning Tool.

Issue When browsing the IP network using the WorkPlace Commissioning Tool, third party devices are displayed in addition to the I/A Series BACnet devices but no information is known about those devices. Product Line TAC I/A Series Environment WorkPlaceTech Commissioning Tool 3rd party BACnet IP & MS/TP devices Cause 3rd party BACnet devices are sometimes connected to the IP network without the knowledge of the engineer  programming the I/A Series system. Resolution When performing a global browse of the IP network, unknown devices are sometimes displayed in the WorkPlaceTech Commissioning Tool device list display.  Since all data columns are not necessarily displayed, some of the device information may not be able to be directly determined. Right-click in the column headers and a menu of available data columns will be displayed. The following columns may be displayed at a minimum to allow identification of the devices on the network as well as the BACnet routing path to those devices:     Instance     Vendor     Model     Router     Network     Address   If the device is a BACnet IP device, the "Address" will be displayed as an IP Address and Port.  For example the address of a BACnet IP device communicating via port 47821 at IP 10.159.34.238 Address   =  10.159.34.238 : 47821   If the device is a BACnet MS/TP device under a BACnet IP device, the address is the MAC address of the device on the MSTP bus and the Router is the address of the BACnet IP router to that device in Hexadecimal numbers.  For example, for MSTP device #4 under BACnet IP Router address, 10.159.34.238 : 47821 10 = 0A, 159 = 9F, 34 = 22, 236 = EC and 47821 = BA CD  Address   =   4 Router      =   0A-9F-22-EC-BA-CD   If the device provides vendor and model information, that information will be displayed in the appropriate columns.

Issue It is normal for a BACnet network port's Poll Service 'Busy Time' property to be greater than 100%? Eg: Product Line I/A Series Environment G3 BACnet Cause The Poll Service is a common component for typical field bus drivers including BACnet.  The Niagara Ax Drivers Guide defines the Poll Service's Busy Time property as: Displays a percentage of time spent by the poll thread actually polling points, across all poll buckets. Includes (in parentheses) a ratio of “(time spent polling/total time since statistics were restarted)”. Given a small amount of time is spent transitioning between poll buckets, and with the thread sleeping to evenly space out polling messages, it is unlikely to ever see Busy Time reach exactly 100%. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling.  Resolution In the case of the Poll Service for a BACnet network port, because two threads are used for polling, it is possible to see a Busy Time approaching 200%. In this case, divide the Busy Time in half to get an average busy time for each thread. In the case of the Poll Service for a Bacnet network port, because two threads are used for polling, it is possible to see a Busy Time approaching 200%. In this case, divide the Busy Time in half to get an average busy time for each thread. actually polling. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling. to evenly space out polling messages, it is unlikely to ever see Busy Time reach exactly 100%. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling to evenly space out polling messages, it is unlikely to ever see Busy Time reach exactly 100%. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling. Given a small amount of time is spent transitioning between poll buckets, and with the thread sleeping to evenly space out polling messages, it is unlikely to ever see Busy Time reach exactly 100%. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling. Includes (in parentheses) a ratio of “(time spent polling/total time since statistics were restarted)”. Given a small amount of time is spent transitioning between poll buckets, and with the thread sleeping to evenly space out polling messages, it is unlikely to ever see Busy Time reach exactly 100%. However, any percentage above 95% indicates that the poll thread is basically spending all of its time actually polling.

Issue USB LON adapter from Echelon (PS3 Part Number:ECH-75010R) is not recognized by Workplace Tech. Environment USB LON adapter (ECH-75010R) Workplace Tech Cause The ldv32.dll file (Open LDV driver) loaded with Workplace Tech (located in C:\Program Files\WorkplaceTech directory) is an older version of the driver and it does not support USB interfaces. Resolution Download the latest version of the LDV driver (153-0212-01A_OpenLDV340.exe) The latest version of the LDV driver can be downloaded from the Echelon website (www.echelon.com) and it contains support for USB devices. In order to download from Echelon’s website, a (free) user account is required. Once it is created, proceed to “Recommended Downloads” and the LDV driver will be listed (towards the bottom) as "OpenLDV 3.4 Network Drivers for Windows Vista/XP/2000/Server 2003 (includes drivers for i.LON 10/100/600 RNI, PCLTA-20/21, PCC-10, and U10/20". The LDV driver is also posted on The Exchange Download Center. Install the new LDV driver Copy the ldv32.dll file from the C:\lonworks\bin directory, and paste it into the C:\ProgramFiles\WorkplaceTech directory. This driver is required for Workplace Tech version 5.6 or earlier. After installing the driver, Workplace Tech will now recognize the USB adapter.

Issue Can a graphical indicator be placed on a Niagara AX or N4 view to indicate when a point is overridden, analog or binary? Product Line TAC IA Series Environment I/A Series AX graphics I/A Series N4 graphics Cause By default, the StatusEffect setting is turned off (None). Change StatusEffect to Color to enable the graphical indicator. Resolution In the properties of the BoundLabel, set the StatusEffect attribute to Color (default is None). This will cause the object to turn purple (the default color) when it is overridden.

Issue Procedure for balancing a parallel fan VAV box with supply side flow sensing, using the WorkPlace Flow Balance Tool (WFBT). Product Line TAC IA Series Environment I/A Series MNB VAV Cause Request from field Resolution In summary, the procedure is to complete the balancing process with the fan disabled then enable the fan and use the verify functions to check operation with the parallel fan running. Perform all steps of the flow balance procedure as usual up through and including the maximum flow balancing and minimum flow balancing. For the first pass at balancing the reheat minimum flow, use the fan control on the screen to turn the fan ON then set the minimum flow setpoint to 0. Verify that the flow as measured by the pressure sensor goes to zero. Measure the total flow manually using the flow hood and adjust the fan speed so that the required airflow is obtained. The easiest way to do this is to take the first set of readings from all the diffusers then adjust the fan speed as needed and then recheck the sum of the new readings to confirm the adjustment is correct. Click the "Restart" button to restart the Reheat Min Flow balancing process. Set the parallel fan to OFF and re-enter the desired Reheat Min Flow setpoint value. Balance the Reheat Min Flow using the normal balance procedure. For reference, see Chapter 5 of the WorkPlace Commissioning Tool and Flow Balance Tool Users Guide (F-27358).

Issue The localhost cannot be opened in the R2 Admin Tool. The error messages: “Cannot open admin session. java.net.ConnectException: Connection refused: connect” is displayed in the popup. The error messages “Niagara service could not be started.” when attempting to start WorkPlace Pro via the console. Product Line TAC IA Series Environment Niagara R2, WorkPlace Pro Cause The WorkPlace Pro PC has AVG software installed. The AVG software stripped out the “niagarad.exe” executable file during the installation of WorkPlace Pro. The Niagara R2 service could not be started without the niagarad.exe file. . Resolution Turn off AVG software and then reinstall the WorkPlace Pro software.

Issue When trying to open the admin tool in Niagara R2 Workplace Pro, the following error message appears: Cannot open admin session Java.net.connect Exception:Connection refused:connect Product Line TAC IA Series Environment Niagara R2 Workplace Pro Cause This error occurs because the local Niagara service is not running. Resolution Open the console of the desired version Type admininstall install /start Now you should be able to log into an Admin tool session.

Issue  Interstation links between UNC and Enterprise Server are not functioning. Product Line TAC IA Series Environment Windows 7 Windows Vista Windows XP Niagara R2 Cause Windows Firewall is enabled by default on desktop operating systems post Windows XP SP1. The Windows Firewall must be configured to allow unsolicited messages such as alarms and inter-station links from UNC's to be received by the Enterprise Server. Resolution WINDOWS FIREWALL OVERVIEW Windows Firewall is a “state-full packet filter” firewall by default. This means that all TCP packets trying to enter a system with the Windows Firewall enabled will be discarded unless those packets are responses to queries from that system, or if the packet is destined for a port that has an exception create for it. In other words, unless an exception is created, or the Windows Firewall is disabled a valid message such as an alarm or an inter-station link from a UNC will be blocked by the Windows Firewall and won’t be received by the Enterprise Server. Windows Firewall allows for exceptions to be created for particular ports and from particular ranges of IP addresses. For example, one could create a rule that accepts unsolicited packets on port 25, but only from the range of addresses from 192.168.0.1 through 192.168.0.254. There are two kinds of exceptions: program exceptions and port exceptions. A program exception is where the Windows Firewall is instructed to open ports that a certain program needs for unsolicited communications. This is the preferred method since Windows Firewall is only open while the program is waiting to receive the connection. In contrast, a port exception is the Windows Firewalls' way of acting like a port-filtering router. In other words, Windows Firewall can be configured to let in any traffic on a particular port whether it's solicited or not. Creating a Program Exception Windows XP Open Windows Firewall from the Control Panel and from the exceptions tab click "Add Program..." Click the browse button Navigate to the c:\Niagara\Version\Nre\Bin folder. Select the file “nre.exe” adding it to the list of programs. To specify which TCP/IP devices can use the port, click Change Scope and select one of the following To allow connections from any device, including those on the Internet, select “Any computer (including those on the Internet)”, and then click OK. (This is the default and least secure option) To allow connections from your local subnet only, select “My network (subnet) only”, and then click OK. (This is more secure than the previous option but will still allow a malicious attack from a PC on the network) To define a custom list, select “Custom list”, and then type a list of IP addresses separated by commas. (This is the most secure option) Click OK. The program will appear selected on the Exceptions tab under Programs and Services. Click OK to finish. Windows 7 Open Windows Firewall from the Control panel then select Advanced Settings: Right click Inbound Rules and select New Rule Select program and click Next. Click the Browse button Navigate to the c:\Niagara\Version\Nre\Bin folder. Select the file “nre.exe” and click Open to add it to the list of programs. Click next. Select Allow the connection and click next Select the Network profiles that the rule applies to and click next Domain The domain profile applies to a network when a domain controller is detected for the domain to which the local computer is joined. If you select this box, then the rule applies to network traffic passing through a network adapter connected to this network. Private The private profile applies to a network when it is marked private by the computer administrator and it is not a domain network. Newly detected networks are not marked private by default. A network should be marked private only when there is some kind of security device, such as a network address translator or perimeter firewall, between the computer and the Internet. The private profile settings should be more restrictive than the domain profile settings. Public The public profile applies to a network when the computer is connected directly to a public network, such as one available in airports and coffee shops. The public profile settings should be the most restrictive because the computer is connected to a public network where the security cannot be as tightly controlled as it is in an IT environment. Name the exception and click Finish Creating a Port Exception Windows XP Open Windows Firewall from the Control Panel and from the exceptions tab click "Add Port..." In the Port number field type 80 Select TCP. Type a short name for the port To specify which TCP/IP devices can use the port, click Change Scope and select one of the following. To allow connections from any device, including those on the Internet, select “Any computer (including those on the Internet)”, and then click OK. (This is the default and least secure option) To allow connections from your local subnet only, select “My network (subnet) only”, and then click OK. (This is more secure than the previous option but will still allow a malicious attack from a PC on the network) To define a custom list, select “Custom list”, and then type a list of IP addresses separated by commas. (This is the most secure option) Click OK twice. The Port will appear, selected, on the Exceptions tab, under Programs and Services. Repeat the procedure to add an exception for port 3011 Click OK to finish. Windows 7 Open Windows Firewall from the Control panel then select Advanced Settings: Select  Connection Security Rules: From right side menu, select “New  Rule” Select Rule Type then select Custom then click Next: Select “Protocol and Ports” then select the TCP protocol type, specify required ports, then click Next. This screen capture     shows the configuration for the I/A Series (Niagara) R2 required ports: On the “When does this rule apply screen, click Next, leaving all three areas checked. On the next screen, name the rule “Niagara 80, 3011 TCP” and click “Finish”. Repeat steps 3 through 7, above, selecting UDP instead of TCP.  All other entries are the same except in step 7 the rule name will be UDP instead of TCP. After completing step 8, the Connection Security Rules will be displayed in the center section of the program window.  You should see the following two rules:  

Issue When trying to open WorkPlace Tech Editor the following error is shown in a pop-up window.   The following error occurred while trying to launch the WorkPlace Tech Ribbon Bar: The add-in could not be installed. Product Line EcoStruxure Building Operation, TAC IA Series Environment Building Operation Workstation (Workplace Tech Editor) I/A Series WorkPlace Tech Cause An installation of the Visio Ribbon has not closed correctly from previous use of WorkPlace Tech Editor or standalone WorkPlace Tech. Resolution Open the Add and Remove function in Windows Select "Program and Feature" Look for an instance of the SE.WorkStation.IA.VisioRibbon when no WorkPlace Tech Editor is running. Right-click and uninstall. Open Workstation and launch WorkPlace Tech Editor  There are other conditions that can cause the ribbon not to run as well.  They are detailed in other articles Similar Error Message Regarding Ribbon Bar  Unable to Load Ribbon 

Issue Getting "An unknown error occurred in the WP4NewProject add-on to Workplace Tech Tool" when trying to download to a device with WorkPlace Tech. Product Line TAC IA Series Environment I/A Series WorkPlace Tech Microsoft Visio (versions noted) Cause Need to enable automation events in Visio. Resolution Below are two options to enable the automation events in Vision 2007 and one option to enable the automation events in Visio 2010 and newer In WorkPlace Tech with Visio 2007: Go to File menu Select Options.  The Visio Options window appears Select Security tab Check the "Enable Automation Events" Click OK Inside Visio 2007: Select Tools and Options. Tools and Options window appears In the Options window, select the Security tab Check the "Enable Automation Events" Click OK In WorkPlace Tech with Visio 2010 through Visio 2021 Go to File menu Select Visio Options. Options window appears Select Advanced from the menu on the left side of the window In the main part of the window, scroll to the "General" section Check the "Enable Automation Events" Click OK   NOTE: This change does not take effect until the WorkPlace Tech Tool or Visio software has been closed and restarted.

Issue Connected to a remote site network via WorkPlace Tech and a VPN connection, but unable to see the sites BACnet devices. No I/A Series MNB-1000s, or any 3rd Party BACnet devices, are found in Workplace Tech or the Commissioning Tool. Product Line TAC I/A Series Environment MNB-1000 WorkPlace Tech (all versions) Cause The VPN does place the connecting WorkPlace Tech PC on the site network, but the BACnet/IP (MNB-1000 and 3rd Party) devices are on a different subnet then the subnet assigned to the WorkPlace Tech PC. Resolution When BACnet/IP devices are on different subnets, BBMD must be used in order for the BACnet/IP devices to communicate across IP subnets. Only one BACnet/IP device can be enabled as BBMD per subnet.   Setup the MNB-1000 as a BBMD device using the Commissioning Tool Open Device Properties of the MNB-1000 controller and select the IP tab. For Device Type select BBMD and save change. Setup WorkPlace Tech to connect to the BBMD device Select Tool from the WPT Select Configure Communication… Select BACnet and click on Change Select IP and click next Select Access a remote internetwork. For Host BBMD Address, enter the IP address of the MNB-1000 which was setup as a BBMD device. Click the Finish button to save changes. You should now be able to see and connect to the I/A Series and 3rd Party BACnet devices using WorkPlace Tech.

Issue Downloaded the WPT (WorkPlace Tech Tool) software.  How do I get a serial number so that I can complete the licensing form displayed with the "Purchase WorkPlace tech Software" program? Product Line TAC IA Series Environment WorkPlace Tech Tool 5.x.x Cause The WPT license generator program requires a "WIBS serial number" so that the license request can be generated. If the field is left blank, the program will not allow the license request to be generated.   Resolution The serial number is provided on purchased CDs so as to provide a method of tracing the manufactured CDs. To license the downloaded version of the Workplace Tech Tool software, you must enter an 8 digit serial number.  It is suggested, although not required, that you enter the current date as the serial number. When using the date as the serial number, enter the four digit year followed by the two digit month followed by the two digit day, i.e., in the format YYYYMMDD. For example, 20230203.

Issue What is the maximum number of devices that can be placed on the MS/TP trunk of the ENC-520, UNC-520 and MNB-1000? Product Line TAC IA Series Environment Niagara R2 Niagara G3 UNC-520 ENC-520 MNB-1000 Cause Unit Load is a measure of the electrical loading of an EIA-485 (MS/TP) network. An EIA-485 network may have 32 unit loads. One unit load consists of one full-load transceiver, two half-load transceivers, four quarter-load transceivers, or eight eighth-load transceivers. Resolution All MNB-xxxx, UNC-xxx, and ENC-xxx devices use quarter load transceivers, which mean that a MS/TP network comprised solely of MNB devices can have up to 128 total devices (1 router plus 127 controllers). The maximum number of BACnet devices allowed per MS/TP trunk, if all devices are quarter-load transceiver, is 127 plus the ENC/UNC or MNB-1000 controller. Note: 32 unit loads times 4 transceivers per unit load equals 128 maximum transceivers per network (32 X 4 = 128). UNC/ENC Resource Limit Although the 128 BACnet devices is the stated maximum for a MS/TP trunk, this maximum is normally not achieved. This is because the number of MS/TP devices that can be placed on a MS/TP bus is limited by the resource limit of the UNC/ENC controller. A shortage of resources will limit the devices on an MS/TP network to a number less than the physical limit. Exceeding the resource limit will negatively affect the UNC/ENC-520s, possibly causing poor performance and resets (of the UNC/ENCs). Reference Appendix A of BACnet Wiring and Networking Practices Guide for additional information.

Issue My Server has a 100,000 alarms and a lot of old trend data.  How can I delete them quickly? Product Line TAC IA Series Environment I/A Series R2 Niagara Cause The APP folder under the station holds all alarm and trended data.  When this folder gets too big, i.e. >500 MB the Server functionality can slow down while working with this large database file. Resolution Stop the Server station Rename the existing APP folder to something other than APP Restart the Server station.  When the Server station restarts it will check for the presence of a folder called APP and when none is found it will create a new one and use that one to archive alarms and trend data. 

Issue Customer wants a customizable permanently installed touch-screen display instead of a computer and web based graphics for display of points from their network of I/A Series BACnet controllers.  They would like to accomplish this without having to create shadow objects in a UNC or ENC. Product Line TAC IA Series Environment I/A Series MNB family of controllers Optional ENC or UNC Cause Customer does not want to deploy computers that would be easily stolen but instead wants to have permanently installed touch-screen displays. Resolution The LoyTec LVIS-ME212 or LVIS-ME215 touch panels can be directly connected to any BACnet-IP or BACnet-MS/TP network and can be linked to any BACnet object on the interconnected BACnet networks including those objects accessible over attached BACnet routers such as an ENC or MNB-1000. Available through the Schneider Electric iPortal online ordering system as LOY-LVIS-ME212 and LOY-LVIS-ME215  

Issue What is the procedure for upgrading the I/A Series G3 software in an I/A Series ENC? Product Line TAC IA Series Environment I/A Series G3 Workbench software on computer (both the old version and new version need to be installed on the computer) I/A Series G3 ENC-520 or ENC-410 Cause Need to upgrade the software that is installed in the ENC. Resolution With the old version of Workbench running on the computer, backup the station running in the ENC.  All required graphic files, etc., stored in the ENC should also be backed up.  Note the station folder name for use in step 5, below. Verify that the license in the ENC is compatible with the new release to be installed. If not, use the License Manager (under the Platform) to install an updated license. If the correct version of the license is not currently available, it must be obtained and installed prior to beginning step 6, below. If the new release of the I/A Series G3 software has not already been installed on the computer, install it now. Verify that the Workbench computer has a license that is version compatible with the new release of the I/A Series software to be installed.  If the license is not version compatible, acquire a new license for the Workbench computer before continuing. Copy the entire named station folder (used in step 1) from the old release Stations folder to the new release Stations folder.  See NOTE below regarding the installation of a version downgrade. Run the "Install Platform Daemon" command from the Windows Start Menu folder for the new version of the software. Open the Workbench in the new version of the I/A Series G3 software and connect to the platform of the ENC to be upgraded. From the Platform menu, open the License Manager and verify that the ENC license has been updated to allow use with the new version of the I/A Series G3 software. Right-Click on the ENC platform in the Workbench tree and select Commissioning Wizard. Complete the commissioning process as documented in the Niagara AX Install and Startup Guide . On the first screen, select the operations to be performed.  The required minimum operations will normally be checked and shown in grey.  The "Install a station..." option needs to be checked if not already checked. Click [Next] to begin the commissioning process.  Continue through the various steps, as required.   When prompted, select the station copied in step 5. When prompted, verify that all required modules are available and are selected for installation. Allow the commissioning process to complete, following the prompts as required. The upgrade is now complete.  Start the station as required. NOTE: Do not use the process to directly downgrade the version of software installed in an ENC.  You must use the Platform "Distribution File Installer" to install the appropriate clean distribution (from the cleanDist folder under the software version to be installed.  Typically, only one clean distribution file will be available to be installed.  Select that file then click the [-> Install] button to downgrade the ENC software.  This process needs to be done as noted in step 5, above, after backing up the station but before beginning the commissioning of the device with the older I/A Series G3 software version.

Issue In MNB-1000 (Plant Controller) firmware Revision 1.50E, the Spanning Tree Protocol is Disabled, by default. All previous versions were shipped with the Spanning Tree Protocol enabled. Product Line TAC IA Series Environment I/A Series MNB-1000 (Plant Controller), firmware Revision 1.50E, and later. Cause In some cases where multiple BACnet routers (eg, MNB-1000, UNC, ENC, etc) were installed on the same BACnet-IP internetwork, having the Spanning Tree Protocol enabled in the MNB-1000 would allow a "router loop". Resolution Be aware that in MNB-1000s with firmware Revision 1.50E and later, the Spanning Tree protocol is disabled, by default. Click here to see the Release Notes for firmware Revision 1.50E . It is always recommended the highest firmware version available for the MNB-1000 be used.  Many issues have been addressed for better functionality.