operating conditions (temperature, line voltage, component variation and
transmitter loading).
The cost of such a power supply can be significantly reduced if, instead of designing
the supply for the maximum possible transmit duty cycle and for the worst case
environmental conditions, the supply can be designed for typical operating
conditions. However, designing for typical operating conditions implies that a
mechanism exists to "manage" the worst case operating conditions such that reliable
operation is assured. This management feature must also address products whose
operating conditions (especially transmit duty cycle) are not defined prior to use in a
network, but rather are controlled by application programs loaded after installation.
The PLT-22 power management feature implements the needed management
functionality by intelligently monitoring the energy storage power supply. Should
the node attempt to transmit too frequently, the power management feature
enforces a limit on the transmit duty cycle by preventing the Neuron Chip from
transmitting until the node's power supply recovers to the point that sufficient
energy is available to transmit a packet. Details of this feature and application
examples are provided in Chapter 5.
When power management is enabled, the PLT-22 transceiver requires a V
A
power supply voltage of 12.9V before it will attempt to transmit a packet.
Products with fixed V
A
power supplies lower than 12.9V should never be
programmed to enable the power management feature as they may never
be allowed to transmit. Likewise a node whose power supply relies on
power management to operate correctly should never be programmed with
the power management feature disabled.
The user can enable or disable power management at the time of channel definition
by selecting a standard transceiver type with a "low" suffix. The only difference
between a set of standard transceiver parameters with the "low" suffix and the
corresponding set without the "low" suffix is that the power management feature is
enabled with the "low" set and disabled with the set without the suffix.
Note that some installation tools load a device's communication parameters as part
of the installation and replacement process and calculate those parameters based on
the channel (rather than the particular device). Such tools can not be used for
systems that contain a mixture of nodes with and without power management
enabled on the same channel.
Tools based on the L
ON
W
ORKS
Network Services (LNS) architecture, such as
LonMaker for Windows Integration Tool, correctly support all configurations of PLT-
22 (and PLT-21) nodes with or without power management. For a tool not based on
LNS, contact your tool vendor to determine if it can support a mixture of power
management and non-power management nodes on the same channel.
Standard Transceiver Types
Four standard transceiver types are defined for the PLT-22 transceiver operating in
the 110 kHz – 140kHz range. These standard transceiver types specify
communications parameters for a PLT-22 (or PLT-20 or PLT-21) node. The
3-4
PLT-22 Transceiver Programming
Summary of Contents for LONWORKS PLT-22
Page 6: ...iv Echelon...
Page 14: ...1 8 Introduction...
Page 67: ...LONWORKS PLT 22 Transceiver s User Guide 5 7 Figure 5 3 Capacitor Input Power Supply Schematic...
Page 92: ...6 10 Design and Test for Electromagnetic Compatibility...
Page 110: ...7 18 Communication Performance Verification...
Page 114: ...8 4 References...
Page 118: ...A 4 Appendix A...
