Rockwell Automation Publication 1715-UM001J-EN-P - December 2020
261
Appendix B 1715-IB16D Digital Input Module Diagnostics
Calculate Threshold and
Resistor Values
To arrive at the correct diagnostic settings, you must know one of the two
values—either the threshold values or the resistor values, and then calculate
the other set of values from the known values.
The following example shows a typical EOL arrangement for an Emergency
Shutdown Device.
Figure 78 - Field Loop Circuit for Line Monitored Digital Input for Emergency Shutdown Systems
(ESD)
You must realize that by virtue of R1 and R2, in combination with the internal
impedance and field switch position of the module, various voltage levels are
produced at the input terminal that the threshold values can characterize.
Knowing the resistor values allows you to calculate the voltage levels to arrive
at the threshold settings.
Use
and
, and the resistor values you choose. to determine
how the system responds to various field wiring conditions, so that the
threshold values can be set. For our example, we used the resistor values in
.
Calculate the Voltage for Off/On Conditions for Threshold Values
The following examples calculate the voltage for an ‘off’ condition with the
switch opened and closed.
Open Switch/Off Condition
With SW1 open, current flows through R1 and R2 (15 + 3.9 k
18.9 k
. We can
calculate the voltage that is present at the input of the input module and by
using a voltage divider circuit, we can calculate the voltage for an ‘off’
condition.
Shield
(if used)
Terminal
Blocks
OV
20
Ω
100
Ω
50 mA
4.99k
Ω
Termination
Assembly
+24V DC
R1
R2
45678
Содержание Allen-Bradley 1715-AENTR
Страница 10: ...10 Rockwell Automation Publication 1715 UM001J EN P December 2020 ...
Страница 114: ...114 Rockwell Automation Publication 1715 UM001J EN P December 2020 Chapter 2 Installation Instructions Notes ...
Страница 134: ...134 Rockwell Automation Publication 1715 UM001J EN P December 2020 Chapter 4 Digital I O Operation Notes ...
Страница 200: ...200 Rockwell Automation Publication 1715 UM001J EN P December 2020 Chapter 6 Configure the Redundant I O System Notes ...
Страница 244: ...244 Rockwell Automation Publication 1715 UM001J EN P December 2020 Chapter 9 Redundant I O System Diagnostics Notes ...
Страница 272: ...272 Rockwell Automation Publication 1715 UM001J EN P December 2020 Appendix C Reconfigure a Module Online Notes ...
Страница 290: ...290 Rockwell Automation Publication 1715 UM001J EN P December 2020 Appendix G History of Changes Notes ...
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Страница 297: ...Rockwell Automation Publication 1715 UM001J EN P December 2020 297 Redundant I O System User Manual ...