SNMP (std) to Metasys N2, and BACnet Multiport Gateway

The BACnet/IP driver allows the FieldServer to transfer data to and from devices over Ethernet using BACnet/IP protocol. The FieldServer can emulate either a Server or Client.

All information in a BACnet system is represented in terms of objects. The Object_Identifier is a 32-bit code that identifies the type of Object (also identified by the Object_Type Property) and its "Instance" number, which together uniquely identify the Object within its BACnet device. Theoretically, a BACnet device could have over four million Objects of a particular type. The Object_Name is a text string, which has a unique capability.

BACnet devices may broadcast queries for devices that contain Objects with a specific Object_Name. This can greatly simplify project setup.

BACnet requires one Device Object to be present in every BACnet device. The Device Object makes information about the device and its capabilities available to other devices on the networks. Before one BACnet device starts control-related communications with another, it needs to obtain some of the information presented by the other device's Device Object. Unlike other Objects, the Device Object's Instance number must be unique across the entire BACnet internetwork because it is used to uniquely identify the BACnet devices. It may be used to conveniently identify the BACnet device from other devices during installation.

Standard object types are used to hold real time data and other information. Each Object Type is referenced by a number, for example 0 represents an Analog Input. See Appendix D.1 for abbreviation list.

Each Object consists of a number of prescribed properties, the main property being the Present_Value. Objects are monitored and controlled through their properties.

The information that follows describes how to expand upon the factory defaults provided in the configuration files included with the FieldServer.

The BACnet Master-Slave/Token-Passing (MS/TP) driver implements a data link protocol that uses the services of the RS-485 physical layer. See the FieldServer BACnet PIC statement for the level of conformance that this driver implements.

All information in a BACnet system is represented in terms of objects. The Object_Identifier is a 32-bit code that identifies the type of Object (also identified by the Object_Type Property) and its "Instance" number, which together uniquely identify the Object within its BACnet device. Theoretically, a BACnet device could have over four million Objects of a particular type. The Object_Name is a text string, which has a unique capability. BACnet devices may broadcast queries for devices that contain Objects with a specific Object_Name. This can greatly simplify project setup.

BACnet requires one Device Object to be present in every BACnet device. The Device Object makes information about the device and its capabilities available to other devices on the networks. Before one BACnet device starts control-related communications with another, it needs to obtain some of the information presented by the other device's Device Object. Unlike other Objects, the Device Object's Instance number must be unique across the entire BACnet internetwork because it is used to uniquely identify the BACnet devices. It may be used to conveniently identify the BACnet device from other devices during installation.

Standard object types are used to hold real time data and other information. Each Object Type is referenced by a number, for example 0 represents an Analog Input.

Each Object consists of a number of prescribed properties, the main property being the Present_Value. Objects are monitored and controlled through their properties. The Analog Input Object is representative of the Objects involved directly with control elements and many of its Properties reflect this.

The information that follows describes how to expand upon the factory defaults provided in the configuration files included with the FieldServer.

This protocol translator/gateway provides a wealth of features to enable data transfer between different devices and networks utilizing serial, Ethernet or LonWorks ports. The extensive library of FieldServer drivers provides easy interoperability with devices and networks used in building automation, HVAC, fire and process control industries.

The FS-B3510 is one of the FS-X30 Series FieldServers designed to meet the needs of system integrators in designing a complete interoperable system. The FS-B30 Series brings together the powerful FieldServer driver library with state-of-the-art gateway design. This FieldServer includes four serial connections (two RS-232, two RS-485), two Ethernet ports, and a LonWorks port. The multiport design allows for serial-to-serial interfaces or interface from mulitple serial products to an Ethernet or LonWorks network. The two Ethernet ports enable the integrator to connect a PC to download configuration changes without disturbing the system connections and without the additional cost of an external hub.

The Metasys® N21 by Johnson Controls network supports communications with a diverse range of devices. Many N2 compatible devices use their own version of the protocol and care must be taken to ensure that the device of interest is covered by the FieldServer implementation.

At present the FieldServer Metasys® N2 driver will support communications with the following devices or classes of devices when acting as a Client:

• N2Open-compliant devices. N2Open is a published N2-compatible protocol enabling 3rd party device vendors to integrate with N2.
• VMA 1400 series (with restrictions)
• DX9100 and XT9100

When acting as a Server the FieldServer Metasys® N2 driver can emulate an N2Open device only.

The SNMP-STD driver allows the FieldServer to transfer data to and from devices over Ethernet using the SNMP Version V1 or V2c protocol. The FieldServer can emulate a Server (SNMP Agent) or Client (NMS Network Management Station).

The FieldServer provides a generic MIB (Management Information Base) file that sets out the OID (Object Identifiers) structure. The FieldServer Enterprise ID is 6347. A selection of standard MIB-2 OID’s are supported to allow interaction with popular Network Management packages.

When configured as an SNMP Agent (Server) the SNMP-STD driver allows SNMP Get, GetNext (walk) and Set commands to access Data Arrays using the Integer type. The SNMP v1 protocol does not make provision for Floats.

The SNMP-STD driver can send SNMP traps. The structure for SNMP Traps is provided in the FieldServer’s generic MIB file.

The FieldServer also supports custom MIBs and the automatic generation of the MIB file. It supports setting a custom enterprise ID, object names and custom traps or informs. In custom configurations the FieldServer supports various data types as specified in Section 6.1 of the Manual.

When configured as a Client, the FieldServer can read objects from the Server using Get, GetNext (walk) or GetBulk commands. The GetBulk command is very useful to transfer large amounts of data. The FieldServer can update objects in Agent using the Set command.

The FieldServer can accept any trap or inform as long as all the objects in the message are encoded with a full OID.

The Client side of the driver is considered as a custom configuration.