Electrical Connections EIA-485 Connections
25
Document 51338 Rev. B 08/24/05 P/N 51338:B
4.2 EIA-485 Connections
Notes:
1. All connections are power-limited and supervised
2. A maximum of 32 LCD-80F annunciators may be connected to
this circuit
3. 6,000 feet (1,800 m) maximum distance @ 18 AWG (0.75 mm
2
)
between the FACP and first LCD-80F, between each LCD-80F
and return to the FACP from last LCD-80F
4. Use overall foil/braided-shielded twisted pair cable suitable for
EIA-485 applications (refer to “EIA-485 Shield Termination” on
page 26, for shield termination information). Six conductor
overall shielded wire may be used for the four EIA-485 wires
and the two power wires. It is, however, strongly recommended
that the power and communication wires be separate whenever
possible
5. Ferrite Core P/N FBD-1 is required to meet FCC Part 15 require-
ments if the EIA-485 wiring is not in conduit
6. The EIA-485 circuit is rated at 5.5 VDC maximum and 60 mA
maximum
7. The LCD-80F annunciator has resistors built into the circuit
board at the In (Terminals 2 & 4) and the Out (Terminals 1 & 3)
for impedance matching. There is no
need for the installer to add
impedance matching resistors
8. Enable FACP communication with the LCD-80F in the FACP
programming if appropriate (refer to FACP manual)
4 3 2 1
7 6 5 4 3 2 1
12345 6
78
Figure 4-2: EIA-485 Connection
P2
P1
+ EIA-485 OUT
+ EIA-485 IN
- EIA-485 OUT
- EIA-485 IN
in from FACP
Out to next LCD-80F or return to
host FACP if last or only annuncia-
tor on the line
Ferrite Core P/N FBD-1 is required (see note 5)
FDU80Bdscdr
LCD-80F
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