Echelon LONWORKS PLT-22, User Manual

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Why Verify Communication Performance?
While each PLT-22 transceiver is verified to meet its full communication
performance capabilities prior to shipment, circuitry external to the transceiver
could compromise the communication performance of the node in which the
transceiver is used. Ways in which communication performance could be
compromised include mis-loaded components, inadequately filtered switching power
supplies, circuitry improperly added between the transceiver's coupling circuit and
the power mains, and deviations from recommended part specifications. Due to the
robust communication capability of the transceiver, it may not be obvious that
communication performance has been compromised when testing in a nominal
environment.
Since compromised performance is generally observable only under
“corner-case” conditions, failure to verify performance prior to deployment
could result in many marginal units in the field before a problem is
detected. It is therefore essential that the communication performance of
every PLT-22-based design be verified prior to field deployment. This can be
accomplished either by self verification, using the procedures given in this chapter,
or by contacting your Echelon sales representative to make arrangements to send the
node to Echelon for confidential evaluation.
This chapter describes a simple "black box" testing methodology for determining
whether or not the communication performance of a PLT-22 transceiver-based
product has been compromised. This procedure works equally well for products
employing L-N or L-E coupling.
Before starting the verification process it is essential that the checklist in
Appendix B be completed in its entirety.
Verification Strategy
An overview of the recommended verification procedure is as follows:
1
Create a controlled power line environment that is isolated from typical power
mains noise and loading.
2
Provide known load impedances at the PLT-22 transceiver's communication
frequencies.
3
Use the PLCA-22 Power Line Communications Analyzer (model 58022) as a
calibrated reference transmitter and receiver.
4
Test the performance independent of the product's application by making use
of the Neuron Chip service pin and internal statistics features. If the product
under test does not have a service pin switch then it will need to be added to
the product for testing purposes.
5
Test for unintentional noise injection and excessive loading by the product
under test. This is to ensure that the device can behave as a “good citizen” on a
power line network.
7-2 Communication Performance Verification