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nodes. For applications which require an even higher receive impedance, refer to
discussions in Chapters 5 and 6.
The 10Vp-p output capability of the PLCA-22 analyzer is used to increase the
sensitivity of the test. The higher output signal allows the 0dB, -3dB, and -6dB
LEDs of the PLCA-22 analyzer signal strength meter to be used for observing signal
strength. These LEDs, unlike the other LEDs in the signal strength meter, are only
3dB apart allowing for better measurement resolution.
A series impedance circuit (figure 7-4) in the output path of the transmitting PLCA-
22 analyzer is used to increase its effective output impedance, thereby preventing its
normally low transmit output impedance from overshadowing the impedance of the
product under test.
1
Set a PLCA-22 analyzer in
Recv
,
UnackPri
, and
C-band
modes (referred to as
the Recv PLCA-22 analyzer) and configured for Internal and Line-to-Neutral
coupling, as shown in figure 7.7.
2
Connect a second PLCA-22 analyzer in
Send
,
UnackPri
, and
C-band
modes
(referred to as the Send PLCA-22 analyzer) and set it for External and Line-to-
Neutral coupling as shown in figure 7.7. Connect the impedance circuit (88.7
Ω
resistor; figure 7-4) and the coupling circuit as shown. This test is best conducted
with the CENELEC protocol turned off in order to provide uninterrupted LED
illumination (set on the send unit's setup screen).
3
Verify
that
Attn
on the SPHY PLCA-22 analyzer is set to 0. Set the number of
packets to be transmitted to 9999k on that unit and set the packet length to 13
bytes. Set
TxVpp: 10V
.
4
Without the UUT connected, press START on the Send PLCA-22 analyzer. A test
should begin and the receive packet count on the Recv PLCA-22 analyzer should
increment with a packet error rate very close to 0%. The signal strength meter on
the Recv PLCA-22 analyzer should have the LEDs up to and including the -3dB
primary signal strength LED illuminated. The 0dB primary LED may or may not
be flashing.
5
Next, connect the UUT as shown in figure 7.7. The -3dB primary signal strength
LED on the Recv PLCA-22 analyzer either should be flashing or illuminated
continuously. If the -3dB primary LED is extinguished, then the UUT's input
impedance is excessively low (<100
Ω
). The impedance of the UUT must be
corrected before proceeding; refer to the node checklist described in Appendix B
for assistance.
7-8
Communication Performance Verification
Содержание LONWORKS PLT-22
Страница 6: ...iv Echelon...
Страница 14: ...1 8 Introduction...
Страница 67: ...LONWORKS PLT 22 Transceiver s User Guide 5 7 Figure 5 3 Capacitor Input Power Supply Schematic...
Страница 92: ...6 10 Design and Test for Electromagnetic Compatibility...
Страница 110: ...7 18 Communication Performance Verification...
Страница 114: ...8 4 References...
Страница 118: ...A 4 Appendix A...