Single-ended encoder interface via open collector, Transistor with 24 vdc pull-up (not recommended), Step/direction and cw/ccw (step up/step down) – Rockwell Automation 1398-DDM-xxx USE MNL/ULTRA 200 DIG.SERVO.DR User Manual

Page 88: Interface specifications

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Publication 1398-5.0 – October 1998

6-24

Interfaces

Figure 6.29

Single-Ended Encoder Interface via Open Collector
Transistor with 24 VDC Pull-up (not recommended)

twisted pair

twisted pair

Ch A

ENCODER

AX+

AX-

14

J1

Drive

BX+

BX-

16

Drive Chassis

Encoder Case

Ch B

24VDC

24VDC

4
2

Supply

Return

ECOM

IX+

IX-

18

Ch I

24VDC

IN751

5.1 V

IN751

5.1 V

IN751

5.1 V

Table 6.21:

Step/Direction and CW/CCW (Step Up/Step Down)
Interface Specifications

Specification

Description

Minimum

Maximum

Signal frequency

(MHz)

Frequency of the input signal.

1

Pulse Width

(nsec)

Time interval the step (CW/CCW) signal
must remain in a single state for detection.

500

Setup Time

(nsec)

Time interval the direction (CW/CCW) signal
must be stable before the corresponding
step (CCW/CW) signal changes state.

500

The following diagram shows the relationship between STEP and DIRECTION inputs.

STEP

INPUT

DIRECTION

INPUT

Direction data must be
steady for this time period.

500 nsec

minimum

500 nsec

minimum

500 nsec in either
high or low state

500 nsec

minimum

500 nsec

minimum

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