adm2491e Analog Devices, Inc., adm2491e Datasheet - Page 15

• Manufacturer Part Number: adm2491e
• Description: High Speed, Esd-protected, Half-/full-duplex, Icoupler Isolated Rs-485 Transceiver
• Manufacturer: Analog Devices, Inc.

TYPICAL APPLICATIONS
Figure 30 and Figure 31 show typical applications of the
ADM2491E in half-duplex and full-duplex RS-485 network
configurations. Up to 32 transceivers can be connected to the
RS-485 bus. To minimize reflections, the line must be
terminated at the receiving end in its characteristic impedance,
RxD
TxD
RxD
TxD
RE
DE
RE
DE
NOTES
1. R
T
ADM2491E
IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE.
ADM2491E
D
R
MASTER
D
R
A
B
Z
Y
ADM2491E
A
B
Z
Y
V
CC
ADM2491E
R1
R2
R
V
T
SLAVE
R
DD
T
R2
R1
NOTES
1. R
2. ISOLATION NOT SHOWN.
A
T
A
RxD
IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE.
Figure 30. ADM2491E Typical Half-Duplex RS-485 Network
Figure 31. ADM2491E Typical Full -Duplex RS-485 Network
R
RxD
R
B
RE
MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 32
B
RE
DE TxD
Z
DE
MAXIMUM NUMBER OF NODES = 32
D
Z
TxD
Y
D
Rev. 0 | Page 15 of 16
Y
ADM2491E
and stub lengths off the main line must be kept as short as
possible. For half-duplex operation, this means that both ends
of the line must be terminated, because either end can be the
receiving end.
A
A
RxD
R
RxD
R
B
RE
B
RE
DE TxD
Z
DE
D
Z
TxD
D
Y
V
Y
DD
SLAVE
ADM2491E
R
R1
T
R
T
R2
Y
Z
B
A
A
B
Y
Z
ADM2491E
ADM2491E
SLAVE
R
R
D
D
ADM2491E
RE
RxD
DE
TxD
TxD
DE
RE
RxD