Four wire rs-485 connections, Rs-485/rs-422 communication comparison – Rockwell Automation 1398-DDM-xxx USE MNL/ULTRA 200 DIG.SERVO.DR User Manual

Page 104

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Publication 1398-5.0 – October 1998

6-40

Interfaces

Four Wire RS-485 Connections

The ULTRA 200 Series drives use a variation of the RS-485 standard,
known as four wire RS-485. Four wire RS-485 uses one differential
signal for host to drive transmissions, and another differential signal
for drive to host transmissions. (The RS-485 standard specifies a
single differential signal for transmissions in both directions.)

The four wire RS-485 configuration also allows the host to use a RS-
422 type interface. Because the host is driving multiple receivers and
receiving from multiple transmitters, RS-422 is limited to multiple
axes connections with 10 or less drives. The figure below summarizes
the four wire RS-485, RS-422, and RS-485 standards.

Figure 6.40

RS-485/RS-422 Communication Comparison

Intro

Four Wire RS-485

Differential
4 Wires
2 Signal Pairs
1 to 32 Transmitters
1 to 32 Receivers

Intro

RS-422

Differential
4 Wires
2 Signal Pairs
1 Transmitter
1 to 10 Receivers

Intro

RS-485 Standard

Differential
2 Wires
1 Signal Pair
1 to 32 Transmitters
1 to 32 Receivers

NOTE:

Not applicable to

ULTRA 200 Series drives

1

2

32

1

2

10

1

2

32

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