R

D

R

DE

RE

D

Y

Z

R

D

R

RE

DE

D

A

B

B

A

Z

Y

R

D

R RE DE D

Z

Y

B

A

Master

Slave

Slave

R(T)

R(T)

R(T)

R(T)

R

D

R

RE

DE

D

A

B

R

D

R

RE

DE

D

A

B

R

D

R

RE

DE

D

A

B

a) Independent driver and

receiver enable signals

b) Combined enable signals for

use as directional control pin

c) Receiver always on

ISO15, ISO35, ISO15M, ISO35M

SLOS580G – MAY 2008 – REVISED MARCH 2015

www.ti.com

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

The ISO15x and ISO35x family consists of RS-485 transceivers commonly used for asynchronous data

transmissions. Full-duplex implementation requires two signal pairs (four wires), and allows each node to

transmit data on one pair while simultaneously receiving data on the other pair. For half-duplex transmission

there is only one pair which shared for both transmission and reception of data. To eliminate line reflections,

each cable end is terminated with a termination resistor, R(T), whose value matches the characteristic

impedance, Z0, of the cable. This method, known as parallel termination, allows for higher data rates over longer

cable length.

10.2 Typical Application

Figure 18. Half-Duplex Transceiver Configurations

Figure 19. Typical RS-485 Network With Full-Duplex Transceivers

18

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Product Folder Links: ISO15 ISO35 ISO15M ISO35M