Specifications

Chapter 8 – PL Smart Transceiver Programming
208 PL 3120/PL 3150/ PL 3170 Power Line Smart Transceiver Data Boo
k
Introduction
Certain parameters of PL Smart Transceivers are programmed by the developer. This chapter provides an explanation of
the various choices and how they are programmed by way of the NodeBuilder
®
Development Tool, Mini EVK
Evaluation Kit, or ShortStack
®
Developer’s Kit.
The factory preprogrammed settings for the PL 3120 and PL 3170 Smart Transceivers are in accordance with the
PL-20N “standard transceiver type” described in this chapter. This allows programming these chips in a system through
the power line network without having to pre-program the parts using a programmer.
Dual Carrier Frequency Mode
Each PL Smart Transceiver incorporates dual carrier frequency capability which allows it to communicate with other
PL Smart Transceiver and PLT-22-based devices, even if noise is blocking its primary communication frequency range.
If impairments prevent communication in this range, a PL Smart Transceiver based device can automatically switch to a
secondary carrier frequency to complete a transaction with other PL Smart Transceiver or PLT-22-based devices.
With the dual carrier frequency feature the last two retries of acknowledged service messages are sent using the
secondary carrier frequency. Thus, in C-band and when acknowledged service is used with three retries (four total tries),
the first two tries are sent using the 132kHz primary carrier frequency. If the last two tries are needed to complete the
transaction, they are sent (and acknowledged) using the 115kHz secondary carrier frequency. Similarly, for A-band
operation the primary and secondary frequencies are 86kHz and 75kHz respectively. A minimum of two retries must be
used if the PL Smart Transceiver is to be able to use both carrier frequency choices. For optimum reliability and
efficiency, Echelon recommends the use of three retries when using acknowledged service messaging with the PL Smart
Transceiver when heartbeats are not used.
When the repeated message service is used, the PL Smart Transceiver leverages the reliability of both carrier
frequencies by alternating between them. In this case, a repeated message with three repeats results in the first and third
packets being sent using the primary carrier frequency, while the second and fourth packets are sent using the secondary
carrier frequency. A minimum of one repeat must be used with the repeated service for the PL Smart Transceiver to use
both carrier frequency choices.
In the C-band mode of operation, every PL Smart Transceiver transmission at the secondary carrier frequency is
accompanied by a simultaneous 132kHz “pilot” signal which older PLT-20 and PLT-21-based devices can use to
recognize that the channel is busy. This pilot signal prevents PLT-20- or PLT-21-based devices (which cannot detect the
115kHz secondary carrier frequency) from transmitting at the same time that a PL Smart Transceiver is transmitting on
its 115kHz secondary carrier frequency.
CENELEC Access Protocol
To allow multiple power line signaling devices from different manufacturers to operate on a common AC-mains circuit,
the CENELEC EN 50065-1 standard specifies an access protocol for the C-band (125kHz to 140kHz). The 132.5kHz
frequency is designated as the primary band-in-use frequency that indicates when a transmission is in progress.
Every CENELEC compliant C-band device must both monitor the 132.5kHz band-in-use frequency and be able to
detect the presence of a signal of at least 86dBµV
RMS
anywhere in the range from 131.5kHz to 133.5kHz which has a
duration greater than or equal to 4 milliseconds. A power line signaling device is permitted to transmit if the band-in-use
detector shows that the band has been free for at least 85 milliseconds. Each device must randomly choose an interval
for transmission, and at least seven evenly distributed intervals must be available for selection. A group of power line
signaling devices is allowed to transmit continually for a period less than or equal to one second, after which it must
cease transmitting for at least 125 milliseconds.
The PL Smart Transceivers incorporate the CENELEC access protocol and the user can enable or disable the CENELEC
access protocol at the time of channel definition. When enabled, the PL Smart Transceiver enforces the CENELEC