
The LPT-11 transceiver supports free topology wiring, freeing the system installer
from the need to wire in a doubly-terminated bus arrangement. Star, bus, and loop
wiring are all supported by this architecture. Free topology wiring reduces the time
and expense of system installation by allowing the wiring to be installed in the most
expeditious manner. It also simplifies network expansion by alleviating the need for
the installer to follow strict rules about stub lengths. Should it be necessary to add
more devices or wire in excess of the system limits, then two or more link power
systems can be interconnected with an inexpensive, physical layer repeater. The
LPT-11 contains built-in circuitry to allow connection to one or more FTT-10A
transceivers back-to-back to make a repeater. The LPT-11 transceiver includes an
integral switching power supply that can f5VDC at up to 100mA. The LPT-
11 transceiver derives its power directly from the switching power supply, leaving up
to 100mA of current for a Neuron Chip, application electronics, sensors, actuators,
and displays. The high current capability of the LPT-11 transceiver eliminates the
need for local power supplies at each device, resulting in equipment and labor cost
savings.
The LPT-11 transceiver is compatible with Echelon's FTT-10A Free Topology
Transceiver and FT 3120
®
/FT 3150
®
Smart Transceivers (referred to hereafter as FT
31xx devices), and these transceivers can communicate with each other on a single
twisted pair cable. This capability provides an inexpensive means of interfacing to
devices whose current and/or voltage requirements would otherwise exceed the
capacity of the link power segment. When equipped with an FTT-10A or FT 31xx
transceiver, these devices can be operated from a local power supply without the
need for additional electrical isolation from the link power network.
Using the LPT-11 transceiver can save literally thousands of hours of development
time compared with a custom-designed transceiver. The LPT-11 transceiver is
designed to comply with FCC, CE, ICES-003, CISPR22, EN55022, EN55024, and
EN61000-4 EMC requirements, minimizing time consuming and expensive laboratory
transceiver testing. As a UL, cUL, and TuV recognized component, the LPT-11
transceiver can be integrated into a product with minimal additional safety testing of
the LPT-11 transceiver module. The LPT-11 transceiver also meets L
ON
M
ARK
®
interoperability standards.
1-2
Introduction