Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 209
access protocol while still maintaining the benefits of the LonTalk protocol. When the CENELEC access protocol is
enabled, overall network throughput is reduced by 11%.
The CENELEC access protocol must be enabled to meet regulatory requirements in countries that follow CENELEC
regulations (i.e., most European countries). It is recommended that the CENELEC access protocol be disabled on
products that will be used in any country that does not follow CENELEC regulations, in order to maximize throughput.
Note that devices that have the CENELEC protocol enabled should not be installed on the same network with devices
that have the CENELEC protocol disabled. In this instance the devices with the CENELEC protocol enabled would be
prevented from transmitting whenever there was heavy traffic from the CENELEC protocol disabled devices. Thus all
of the devices on a single channel should either have their CENELEC protocol enabled or they should all have it
disabled. A CENELEC Configuration Library is available at www.echelon.com/downloads
. This library can be used
with the NodeBuilder or Mini EVK tools to control support for the CENELEC protocol at runtime. The PL 3170 Smart
Transceiver includes the CENELEC Configuration Library function in ROM.
CENELEC regulations do not specify an access protocol for use in the CENELEC A-band. When programmed with the
A-band transceiver parameters described later in this chapter, the internal CENELEC access protocol for the PL Smart
Transceiver is disabled. With this selection, an active Band-In-Use signal will not prevent a PL Smart Transceiver from
transmitting.
Power Management
PL Smart Transceivers incorporate a power management feature that supports the design of low cost power supplies in
very cost sensitive consumer applications such as networked light dimmers, switches, and household appliances. This
class of application typically requires only occasional low-duty cycle, transmission from the device. Power supplies for
these devices can take advantage of the very low receive current and wide V
A
supply range of the PL Smart Transceiver
to charge a capacitor during receive mode, and then use the energy stored on the capacitor for transmission. With this
feature the continuous current rating of the power supply can actually be less than the current required for transmission
since it only needs to support the receive mode current of the device—plus a modest amount to recharge the capacitor.
Examples of these “Energy Storage Power Supplies”, and a detailed description of how they work, are provided in
Chapter 5.
In order for a device incorporating an energy storage power supply to function properly it is essential that the device not
be required to transmit more than about 10% of the time so that there is sufficient time for the supply to recharge the
capacitor between transmissions under worst case conditions for the supply. The power management feature built into
each PL Smart Transceiver monitors the V
A
supply voltage and, when enabled, automatically regulates the flow of
queued packets to maintain the V
A
supply above its required minimum level. Should the device attempt to transmit too
frequently, the power management feature enforces a limit on the transmit duty cycle by preventing the PL Smart
Transceiver from transmitting until the power supply of the device recovers to the point that sufficient energy is
available to transmit a packet. Details of this feature are provided in Chapter 5.
The user can enable or disable power management by selecting how the Out-Of-Gas (OOGAS) pin of the PL Smart
Transceiver is connected and by the “standard transceiver type” that is selected at the time of channel definition. If the
OOGAS pin of the PL Smart Transceiver is connected directly to its VCORE pin then power management is disabled
independent of the standard transceiver type that is used. If the OOGAS pin of the PL Smart Transceiver is connected to
the resistive voltage divider specified in the selected hardware reference design, then the user can enable power
management at the time of channel definition by choosing 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 whether the power management feature is selected or not. Enabling power management requires
both, use of the specified OOGAS voltage divider and a standard transceiver type with a “LOW” suffix.