Figure 1.1
Free Topology Link Power System Example
LPT-11 Link Power Transceivers located along the twisted wire pair include integral
switching power supplies. These supplies regulate the voltage on the twisted pair
down to +5VDC at currents up to 100mA for use by the Neuron Chip and the various
sensors, actuators, and displays. If a high current or high voltage device must be
controlled, then the +5VDC power can be used to trigger an isolating high current
triac, relay, or contactor.
The integral power supply does away with the need for a local AC-to-DC power
supply, charging circuit, battery, and the related installation and labor expenses.
The savings in money and time that results from eliminating the local power supply
can be up to 20% of the total system cost; the larger the system, the greater the
savings. Moreover, if standby batteries are used, then additional savings will be
realized throughout the life of the system, since only one set of batteries will require
service.
The link power system uses a single point of ground, at the LPI-10 module, and all of
the LPT-11 transceivers electrically float relative to the local ground. Differential
transmission minimizes the effects of common mode noise on signal transmission. If
grounded sensors or actuators are used, then either the communication port (CP) or
the I/O lines of the Neuron Chip must be electrically isolated.
Unlike bus wiring designs, the link power system uses a wiring scheme that supports
star, loop, and/or bus wiring (figure 1.2). This design has many advantages:
1. The installer is free to select the method of wiring that best suits the installation,
reducing the need for advanced planning and allowing last minute changes at
the installation site.
1-4
Introduction