Over the last months I’ve been asked to explain why our integration partners should use the S4 Open: BACnet-N2 Router instead of the BACnet interface provided by a N30 or NAE, using a JCI Facility Explorer, or using a Tridium platform with on on-board N2 driver. There are a lot of different ways to answer this question and to be complete you need to address both organizational and technical issues.
Case 1: The relationship between the building owner and Johnson Controls is broken beyond repair and the building owner simply wants to move in a new direction. Once a building owner has decided to move away from Johnson Controls our S4 Open Appliances provide a very cost effective way to perform that migration over time in a way that salvages your investment in Metasys® equipment, enhance the capabilities of the Metasys® network, and extend the useful life of the N2 field devices.
Case 2: Publish points to BACnet IP using a N30 Supervisory Controller.
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There is not a replacement for the N30. When it eventually dies you need to find a replacement on the used market as long as they are available. Installing the N2 Router removes this risk
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If JCI is cooperative, or you have the skills internally, you can add points you need to the N30 that may not originally been defined in the head end. This issue sometimes becomes a major stumbling block depending on the organizations and personalities involved.
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The N30 has limited memory and supports a limited number of points. Once you reach this limit you need to look for another approach.
Case 3: Publish points to BACnet IP using a NAE Supervisory Controller.
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This is certainly preferable to the N30 approach because this platform is current technology.
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You have the same issue with JCI dependence as with the N30.
Case 4: Publish points to BACnet IP using a JCI Facility Explorer Supervisory Controller
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This is a JCI branded Tridium JACE that has some custom JCI modifications and a N2 driver added by JCI.
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It is based on the Tridium Niagara Platform so there is a large base of support people available.
Case 5: Publish points to BACnet IP using a generic Tridium JACE (or soft JACE) with a 3rd party N2 driver installed.
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The JACE has to carry the load of performing the gateway functionality as well as all of the application and user interface functions.
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We have not seen any 3rd party N2 drivers that have all the capabilities of our S4 Open Appliances.
Case 6: Publish points to BACnet IP using the S4 Open: BACnet-N2 Router
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The N2 Router products expose all N2 device points to the new head end. Even those that JCI doesn’t normally expose to their operator workstation such as tuning parameters.
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The N2 Router products remove all support dependencies on JCI for the head end.
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The N2 Router products work independently of any database, priority, or security settings in the Metasys supervisory controller.
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The N2 Router products can set you up for a very cost effective integration in the short term and a migration away from Metasys® N2 devices longer term.
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The N2 Router products allow your new head end to co-exist with the legacy Metasys® head end. This becomes more important as the integration projects become larger and more complex. No other product has this capability.
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The N2 Router can force the N2 data stream from legacy Metasys® supervisory controllers (NCM, for instance) to participate in the BACnet priority array mechanism. No other product has this capability
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The N2 Router can provide a replacement for the Metasys® “Passthrough” option for the configuration and commissioning utilities. This will be even more versatile than the original offering from JCI as it is not restricted to the Metasys® Operator Workstation. JCI tried to provide this on their Tridium JACE based Facility Explorer but withdrew support after they could not make it reliably work (see discussions on the HVAC-Talk forum). Other N2 drivers for the Tridium platform do not offer this capability. This enhancement will be released in Q2, 2012.
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The N2 Router currently publishes all points from all N2 devices under a single BACnet device defined by the BACnet-N2 Router itself. An enhancement released in Q1 2013 adds the capability to publish each N2 device as its own BACnet device within a virtual BACnet network.
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The N2 Router supports any N2 device that you will find on a N2 bus including N2 Open, VMA, Vendor Devices, Metasys Integrator, and Centaurus Integrator.
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The N2 Router allows you to direct Read, Write, Override, and Release transactions for any point limited only by the programming in the N2 device.
The list goes on. There are times on smaller or less complex projects where you can very successfully utilize BACnet IP from the N30 or NAE. There are other times where the additional power and features of the BACnet-N2 Router make a huge difference by lowering your risk and providing a very effective migration path. Each project has different requirements.