Honeywell Midas User Manual page 92

10.2 LonWorks
®
10.2.1 LonWorks
®
LonWorks is a communications protocol developed
®
by Echelon Corporation which facilitates peer-to-
peer communications in a control network. The
Midas gas detector is available with an optional
®
LonWorks interface.
®
The Midas uses the Free Topology (FT) physical
®
layer which communicates at 78 Kbaud. Each FT
segment can contain up to 64 nodes and up to
2.7 Km of cable. Routers permit expansion of the
network to multiple segments.
The Midas LonWorks
®
functional blocks, 19 network variables and 2
network configuration inputs. It is designed for
compliance with LonMark guidelines version 3.2.
However, it is not LonMark certified. The LonMark
representation of the interface is shown in Diagram
10-3.
Information on LonWorks
echelon.com. Information on LonMark can be found
at www.lonmark.org. Many commercial LonWorks-
compatible products can be found at
com.
Software
Overview
interface contains 2
®
can be found at
®
www.engenuity.
Diagram 10-3. LonMark Diagram
nviRelay1
SNVT_lev_disc
nviRelay2
SNVT_lev_disc
nviRelay3
SNVT_lev_disc
nviReset
SNVT_lev_disc
nviRequest
nv1
SNVT_obj_request
nciMaxSendT
cp22
SNVT_elapsed_tm
nciMinSendT
cp24
www. SNVT_elapsed_tm
10-4
Midas Gas Detector
®
MIDAS LonWorks Gateway Device
Open-loop sensor Functional Block
nv1
Mandatory
Implementation-Specific
SNVT_lev_disc
SNVT_lev_disc
nvoAlmThresh1
nvoAlmThresh2
SNVT_elapsed_tm
SNVT_lev_disc
nvoGasSelection
Node Object Functional Block
nv2
SNVT_obj_status
Mandatory
Implementation-Specific
nv3
Virtual Function Block
nvoConc
SNVT_ppm_f
nvoAlm2
nvoAlmL
nvoAlmS
SNVT_switch
SNVT_ppm_f
SNVT_ppm_f
nvoCellLife
nvoFaultD
nvoFaultS
SNVT_switch
SNVT_count
nvoMonState
SNVT_state
nvoNstat
SNVT_state
nvoStatus
nvoChkSum
SNVT_count