Specifications

75
LonWorks
®
Options for GML 20 and 20T
Series CO
2
Transmitters
SIGNIFICANT SAVINGS
Vaisala's GML 20 and GML 20T are interface modules
for distributing signals from GM 20 series transmitters
digitally to a LonWorks® network over a twisted pair.
The GML 20 module distributes CO
2
signals; the GML
20T module distributes both CO
2
and temperature
signals. The GML 20T module can be used with the
GMW 21 transmitter only. The use of these modules
and GM 20 series transmitters with a LonWorks®
networked control system contributes to considerable
savings in cabling, installation and maintenance costs.
INTELLIGENT LonTalk
®
PROTOCOL
In a LonWorks® network, devices called nodes
communicate with each other using the LonTalk®
protocol. Every node consists of a Neuron® chip and
a transceiver. The Neuron® chip is a microprocessor
which contains an application program and
LonTalk® protocol. The transceiver adapts the
Neuron® chip into the hardware environment used.
The nodes communicate with each other, sending
messages containing the value of the desired vari-
ables.
With Vaisala modules, these variables are CO
2
(GML
20) or CO
2
and temperature (GML 20T). Some
network variables are so-called configuration vari-
ables, which are used to define the behavior of the
node. With the GML 20 and GML 20T, they are used
to designate how much the temperature and/or
carbon dioxide level must change before a measured
value is sent again.
GML 20 GML 20T