36
Rockwell Automation Publication 1734-UM013J-EN-P - July 2014
Chapter 2
Safety Inputs, Safety Outputs, and Safety Data
Tachometer Mode
In Tachometer mode, the module measures digital pulses between 0 and 24V
DC and converts them into a frequency or pulses per second. Therefore, you can
use 24V DC proximity sensors or 5V DC encoders, for example. The
Tachometer function does not sense direction, so using a differential encoder will
not yield direction data. Tachometer mode could be used, for example, to
measure rotational speed of an axis connected to a gear.
Tachometer mode can operate as SIL 2 single-channel. SIL 3 is achievable by
using two sensors, the dual-low detection parameter, and user program logic.
Safety reaction time is dependent on the signal frequency.
Figure 15 - Sensor Pulses in Dual-channel Configuration
Signal Measurement
The edge-to-edge time of the pulse determines the frequency of the signal in
pulses per second. The frequency range is 1 Hz…1 kHz.
In Tachometer mode, you define how the signal is measured, either on the falling
(non-inverted) or rising (inverted) edge. For NPN-style sensors (sensor sinks),
use falling edge. For PNP-style sensors (sensor sources), use rising edge.
Depending on your application, you may need to install an appropriately-sized
pull-up resistor for falling-edge signal measurements or a pull-down resistor for
rising-edge signal measurements.
IMPORTANT
When using two sensors in a dual-channel configuration, position the sensors
to make sure the low pulses occur at different times. If you have configured the
module for dual low detection and both sensors are low at the same time, a
fault will be declared.
Low pulses are offset.
Sensor 1
Sensor 2
Low pulses occur at the same time, causing a fault.
Sensor 1
Sensor 2
Содержание Allen-Bradley 1734-IB8S
Страница 1: ...POINT Guard I O Safety Modules Catalog Numbers 1734 IB8S 1734 OB8S 1734 IE4S User Manual ...
Страница 4: ...4 Rockwell Automation Publication 1734 UM013J EN P July 2014 Summary of Changes Notes ...
Страница 10: ...10 Rockwell Automation Publication 1734 UM013J EN P July 2014 Table of Contents ...
Страница 14: ...14 Rockwell Automation Publication 1734 UM013J EN P July 2014 Preface Notes ...
Страница 22: ...22 Rockwell Automation Publication 1734 UM013J EN P July 2014 Chapter 1 POINT Guard I O Overview Notes ...
Страница 150: ...150 Rockwell Automation Publication 1734 UM013J EN P July 2014 Chapter 8 Replacing POINTGuard I O Modules Notes ...
Страница 180: ...180 Rockwell Automation Publication 1734 UM013J EN P July 2014 Appendix C Specifications Notes ...
Страница 186: ...186 Rockwell Automation Publication 1734 UM013J EN P July 2014 Appendix D Safety Data Notes ...
Страница 190: ...190 Rockwell Automation Publication 1734 UM013J EN P July 2014 Appendix E Configuration Parameters Notes ...
Страница 204: ...204 Rockwell Automation Publication 1734 UM013J EN P July 2014 Appendix G History of Changes Notes ...
Страница 211: ......