L-Gate User Manual 11 LOYTEC
Version 3.2 LOYTEC electronics GmbH
1 Introduction
1.1 Overview
The L-Gate is a high performance, reliable and secure network infrastructure component
that provides data access to a defined set of data points, which are mapped from one
control network technology to another control network technology. In particular, the CEA-
709/BACnet Gateway (LGATE-900) implements mappings between a set of CEA-709
network variables (NVs) and a set of standard BACnet server objects. Which NVs are
mapped to BACnet objects can be configured by an LNS plug-in or stand-alone
configuration software. Easy to understand diagnostic LEDs allow installers and system
integrators to install and troubleshoot this device without expert knowledge and dedicated
troubleshooting tools. The LGATE-900 is equipped with a 100-BaseT Ethernet port (IP),
an FT-10 port (CEA-709), and an RS-485 port (MS/TP). The device is fully compliant with
ANSI/CEA-709 and ENV14908, ANSI/ASHRAE-135-2004 and ISO 16484.
On the CEA-709 side of the L-Gate, there can be up to 1000 NVs. The NVs can be bound
in the CEA-709 network or operated as “external NVs”. External NVs are polled or
explicitly written to without allocating static or dynamic NVs on the L-Gate. In this case,
address information is supplied by the configuration software by importing e.g. a CSV file.
As communications media on the CEA-709 side, the L-Gate supports either the FT-10
channel or an CEA-852 channel (IP channel over the Inranet/Internet). Which of the two
interfaces is used is configurable. The CEA-852 interface can be used behind NAT routers
and firewalls, which allows seamless integration in already existing Intranet networks. It
supports DHCP even with changing IP addresses in an Intranet environment.
The BACnet objects on the L-Gate can be of the type analog input/output, binary
input/output, and multistate input/output. There can be up to 750 of such objects. They are
mapped to NVs as configuraed by the Gateway configuration software. This software is
able to automatically create BACnet object as counterparts to NVs. In particular, BACnet
properties such as Object_Name, Description, Units, Max_Pres_Value, Min_Pres_Value,
Resolution, Number_Of_States, and State_Text are derived from the Standard Network
Variable Types (SNVTs)
1
. Further, the automatically assigned default values can be edited
in the configuration software. BACnet properties updated during run-time by the gateway
are Present_Value, Status_Flags, Reliability, Out_Of_Service. Structured NVs are mapped
to one BACnet object per structure member. The BACnet server objects are accessible
from the BACnet network. In addition, the L-Ggate also includes BACnet client
functionality. For each server object a “client mapping” can be defined. These mappings
specify other BACnet objects on the network where the L-Gate can read values from (poll
or COV subscribe) or write updates to.
1
This is based on the recommendation in CEN/TS 15231:2006.
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