S4 Open: BACnet-N2 Router 1.30 Release Guide

Release 1.30 of the S4 Open: BACnet-N2 Router and S4 Open: OPC-N2 Router adds many significant feature enhancements, performance improvements, and bug fixes to the core products and S4 Open: Management Console. Many of the enhancements are BACnet specific; however, enhancements and bug fixes to the N2 integration and core services apply to both BACnet and OPC products. This version will be delivered for all new product orders starting in January, 2016. Existing customers with an active Software Assurance program subscription are eligible for an upgrade under that program. If your Software Assurance subscription is expired, request a quote for a subscription renewal from your distributor or support contractor.

Current production release 1.19 was introduced in early 2014. Versions 1.20, 1.21, and 1.22 were major milestones or field test versions in the development of 1.30 but were not released for production. Over the last 1 ½ years our newsletter, The Gateway, covered the details of many of the enhancements included in 1.30. This document provides an orientation and introduction to 1.30 and will not duplicate that level of detail. Please refer to http://www.thes4group.com and search for the topic of your choice or refer to the documentation delivered with the system.

This document will walk you through the user interface of 1.30, highlighting the new features and summarizing some of the existing features to assist in system installation and configuration.

System Level BACnet Settings

These features apply to the N2 Router itself. The Appliance acts as a BACnet router and needs to identify itself to the BACnet enterprise with the BACnet Network Number that it will reside in and its own unique Device ID. The BACnet-N2 Router can serve as a BBMD for the local IP subnet or register as a BACnet Foreign Device to the BBMD in another IP subnet.

BACnet Properties

BACnet Virtual Network Number

Each S4 Open: BACnet-N2 Router needs to be assigned a Virtual BACnet Network Number that is unique in the BACnet enterprise. All discovered N2 devices will be published as Virtual BACnet Devices under this network number. BACnet routing algorithms use this network number to locate the N2 Router when accessing the content in the BACnet Virtual Devices it hosts.

Building Control Network

Customizing the BACnet Environment

This tab allows you to configure the features, services, and options enabled for the publishing of Virtual BACnet devices to BACnet IP by the S4 Open: BACnet-N2 Router. By default, all features, services, and options are enabled.

BACnet COV support is new for this release. Enabling BACnet COV causes the S4 Open: BACnet-N2 Router to advertise support for both Unconfirmed COV and Confirmed COV services. Subscriptions to these services are initiated by one or more BACnet clients. The Redundant COV Notifications should always remain selected and cause the BACnet-N2 Router to respond to each COV Subscription with a COV Notification to the subscribing BACnet application. This ensures that the BACnet client and N2 Router are always in sync on the status of COV subscriptions.

BACnet Tab on Ethernet

Transparent BACnet Caching is a new S4 Open Appliance service for 1.30. This is an S4 Open: BACnet-N2 Router feature (not a BACnet service) that disconnects the operation of the N2 field bus from the BACnet transaction stream submitted to the BACnet/IP interface. This feature dramatically improves BACnet client performance, and the user experience, by responding to transactions almost instantaneously. Behind the scenes, the S4 Open: BACnet-N2 Router schedules subscriptions to this service, manages the field devices, and maintains data values in the cache. With the introduction of Transparent Caching it is no longer necessary to add extra time to the BACnet client APDU Timeout and Segment Timeout to accommodate the round trip time to retrieve data from N2 field devices. This feature should be disabled only for diagnostic purposes at the direction of your distributor or support contractor.

Live Point Monitoring

Live Point Monitoring option is a global option for the Management Console. Previously, there were no properties on the S4 Open: Management Console node of the navigation structure so be careful not to miss this option.

Live Point Monitoring

This option applies to the Live Point Monitoring display of all devices in the Building Control Network on all S4 Open Appliances displayed by this management console.

Live Point Monitoring uses BACnet COV, BACnet Polling, or native Windows DCOM communications to request data values from the field devices, with precedence being applied in this order. By default, BACnet COV is disabled and BACnet Polling is enabled for most efficient operation. On the BACnet Tab, you have the option of disabling the use of any of the BACnet access methods if you desire. If all BACnet methods are disabled, native Windows DCOM communications will be utilized.

Live Point Monitoring Method Selection

These options only apply to the Live Point Monitoring feature of the S4 Open: Management Console. This feature is implemented as a BACnet client and is independent of the BACnet Operator Workstation or BACnet global controller selection of access method. i.e. The S4 Open Management Console could be gathering its data by BACnet COV subscription and your BACnet OWS can simultaneously be requesting data by BACnet polling. Typically, these settings should not be changed except when requested by your distributor or support contractor.

If enumerations are defined for Boolean (On Text / Off Text) or Multistate points (State_Text) the points will be displayed with their evaluated states instead of using the numeric value for the point. The Present Value column in the point detail pane will be displayed only if Enable Live Point Monitoring is selected.

The BACnet OID column is new and always displays the BACnet Object Type and Instance Number for the point. With this release, BACnet instance numbers are coded in the associated Device Template and will not change unless explicitly edited by the installer on the BACnet tab of the point properties page, or in the associated Device Template.

Point List Columns

The content of the point detail pane can be conveniently exported to a spreadsheet using the right click “Export List” option from the device folder in the navigation pane.

Black Box Recorder

The Black Box Recorder is a built-in diagnostic and support tool that can be used at the direction of support personnel to gather a snapshot of the system state and approximately the last 200 BACnet and N2 transactions for diagnostic purposes. The recorder results are stored in a file for later transmission via email to the requesting support personnel.

Black Box Recorder

System Watchdog

The system watchdog is an independent process running in the background that monitors all critical application threads and kicks in if it detects an unresponsive feature or service. The watchdog initiates a therapeutic reboot of the system and generates a Black Box Recorder report that will be presented to the operator the next time they visit the S4 Open: Management Console for transmission to S4 for analysis.

What’s In Your Configuration?

The new configuration tab provides a summary of the discovered configuration loaded into the N2 Router.

Configuration Information

Optimizing the Configuration Database

This new option audits the Device Template catalog and deletes any templates that are not assigned to a device object. You should run this function after completing the Configure Wizard, manually assigning any necessary templates, and confirming that your configuration is complete. This frees up valuable system memory that can be utilized by the system for handling live traffic.

Optimize Function

System Performance Monitoring

The Performance tab now includes a CPU meter.

CPU Meter

Smart Data Points

Smart Data Points are a generic capability that can be utilized to perform almost any data transformation during the BACnet (or OPC) read or write process. They are implemented using a combination of Virtual Data Points i.e. points that have a presence only in the S4 Open Appliance and a JC BASIC-like scripting language that enables you to apply algorithms to underlying native N2 points. These algorithms are triggered by the BACnet (or OPC) read and Write requests to the Smart Data Point. These points are published to BACnet (or OPC) and are indistinguishable from the native N2 points in the client interface. With this capability you can give the published device a personality much different than the underlying native N2 device.

Customizing BACnet Virtual Device / Point Attributes

Engineering Units can now be specified for Analog data points. Selection of Units can be made by clicking on the Units link and navigating to the desired enumeration. This selection is independent of the configured Metasys® database and is published to BACnet using standard Engineering Units codes.

Point Properties

For Boolean or Multistate points, the On Text and Off Text and State_Text can be specified or edited by selecting Enumeration in the Units link and then specifying the desired states.

Setting State Text

Multistate points are supported using Smart Data Points in the Device Template for N2 devices.

Smart Data Points

Metasys® starts numbering multistate points at 0 but the BACnet standard requires MSI, MSO, and MSV points to start at 1. The scripting technology of Smart Data Points enables the S4 Open: BACnet N2 Router to automatically make this adjustment. These points have been added to the S4 Device Templates for release 1.30.

BACnet Name

With release 1.30 all point definitions in our Device Templates have been updated to include a BACnet Name field. This option specifies the name that the BACnet-N2 Router publishes to BACnet for the point. If the BACnet Name field is not used, the default name published to BACnet is the Object Name for the point which is constructed by concatenating the N2 Device Name, “/”, and the N2 Point Name. This level of specificity became redundant when the BACnet-N2 Router began publishing each N2 device as a Virtual BACnet device.

BACnet Name

New Device Template Catalog

Default values for the BACnet Name, On Text, Off Text, and State_Text, and Smart Data Points are included in the S4 Device Template definitions for 1.30. In order to automatically take advantage of these features you need to update the device template catalog after upgrading the system firmware and management console. Use the Import function from the Device Template window to import the new definitions.

Template Catalog

Customizing N2 Bus Communications

This feature specifies the amount of quiet time between transactions on the N2 bus to optimize overall N2 bus performance. This parameter should only be changed at the direction of your distributor or support contractor.

Interleaving Time Setting

Creating Unique Device IDs for Virtual BACnet Devices

The Configure Wizard discovers devices on the N2 bus, creates corresponding Virtual BACnet devices, sets up routing tables, assigns Device Templates, and initiates Publishing to BACnet/IP. By default, the N2 address of each discovered N2 device is used to generate the BACnet Device ID for the corresponding Virtual BACnet device. As an aid to creating unique Device IDs, the Configure Wizard will prompt the user for an Offset Value that will be added to the N2 address to generate the Device ID.

Configure Wizard Completion

As a best practice we recommend specifying an offset value with the rightmost 3 digits 000 and the leftmost digits reflecting the Virtual N2 Network Number assigned to the S4 open: BACnet-N2 Router. Using this convention allows you to conveniently determine the N2 Router hosting the N2 bus and the N2 device address of the originating N2 device.


This release prepares the S4 Open: BACnet-N2 Router and S4 Open: OPC-N2 Router for enterprise level, complex integrations with high point count and data rate requirements. It also prepares our S4 Open appliances for supporting several new integrations by implementing many of the concepts outlined in ANSI/ASHRAE Addendum al to ANSI/ASHRAE Standard 135-2012 Best Practices for Gateway Design.