User`s guide

LONWORKS LPT-10 Transceiver User’s Guide 2-11
WAKEUP_OUT pin will be triggered with a period from 1 to 100 seconds, respectively,
with a tolerance of 20% of the period. The tolerance for the capacitor must be added to
this tolerance to obtain the overall tolerance of the output period.
The WAKEUP_OUT pin must be pulled high either with the Neuron Chip’s internal
pullup or with an external resistor. If the wake-up timer is not used, the
WAKEUP_CAP pin must be grounded.
Physical Layer Repeater
In the event that the limits on the number of transceivers or total wire distance are
exceeded, then a link power physical layer repeater (figure 2.4) can be added to
interconnect two link power network segments and double the overall system
capability.
Expansion
Link Power Network Segment
Link Power
Repeater
FTT-10
Transceiver
LPT-10
Transceiver
Link Power Network Segment
Figure 2.4 Two-Way Repeater
The LPT-10 transceiver can be configured as a physical repeater using the RX_ACTIVE
pin. When connected to an FTT-10 transceiver on a second link power network segment,
the two transceivers will act as physical layer repeaters and transmit packets between
the two network segments. The FTT-10 provides isolation between the two segments
(isolation can also be achieved with optical isolators and buffers between two LPT-10
transceivers but with greater circuit complexity and cost). The RX_ACTIVE pin
indicates that a packet is being received, and serves as a transmit enable indicator for
the second transceiver.
Figure 2.5 shows the schematic for a two-way repeater, and figure 2.6 shows the
schematic for a four-way repeater. A packet that is received on any network segment is
retransmitted on the other(s). The repeater derives its operating power from the link
power network segment that is connected to the LPT-10 transceiver. Component
selection and layout information for the FTT-10 may be found in [5], chapter 2.