Normally closed input pulse testing – Rockwell Automation 440C Guardmaster 440C-CR30 Configurable Safety Relay User Manual User Manual

Page 36

Rockwell Automation Publication 440C-UM001C-EN-P - November 2014

Chapter 5

Pulse Testing

Figure 18 - Test Sequence

Normally Closed Input Pulse
Testing

Terminals 12…17 can be configured to generate test pulse outputs. These signals
are used to test for short circuits in the wiring to 24V DC, 0V and between two
channels that are wired to separate test pulse sources (one channel that is sourced
from an odd number terminal [13, 15, and 17], and the other one from an even
number terminal [12, 14, and 16]).

The CR30 generates three distinct pulses, called A, B, and C. Each pulse is 1.7 ms
wide. Pulse Test B immediately follows Pulse Test A. Pulse Test C immediately
follows Pulse Test B. The pulse tests are repeated every 25 ms.

The timing diagram in

Figure 19

shows an example of the pulse testing when the

respective terminals are configured for A, B, and C.

Figure 19 - Timing Diagram

Terminal 12

Terminal 13

Terminal 14

Terminal 15

Terminal 16

Terminal 17

500ms intervals

IMPORTANT

Safety systems requiring a Category 4 structure per ISO13849-1 and SIL 3
rating per IEC61508 must use pulse testing for the dual channel N.C. contacts.
Pulse testing for Category 3, 2, and 1 structures and SIL 2 and 1 ratings is
recommended.

Terminal 13 - B

Terminal 14 - C

Terminal 12 - A

24V

25ms

1.7ms

24V

Terminal 16 - B

Terminal 17 - C

Terminal 15 - A

24V