Latching Inputs - Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual

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28 I/O Configuration

Latching Inputs

Publication 1763-RM001C-EN-P - October 2009
The following table shows sample Analog Signal and Data Word values
using the nominal transfer function formula:
N=Vin x 1023/10 where Vin (analog signal) is in volts (V)
Analog Signal Data Word
0V 0
5V 512
10V 1023
Converting Analog Input Data
Analog inputs convert voltage signals into 10-bit values. To determine an
approximate voltage that an input value represents, use the equations
shown below.
10V
----------- - × inputvoltage V ( )
inputvalue
=
1023
For example, if an input value of 300 is in the input image, the calculated
value is:
10V
----------- - × 2.9326 V ( )
300
=
1023
The MicroLogix 1100 controller provides the ability to individually
configure inputs to be latching inputs (sometimes referred to as pulse
catching inputs). A latching input is an input that captures a very fast
pulse and holds it for a single controller scan. The pulse width that can be
captured is dependent upon the input filtering selected for that input.
The following inputs can be configured as latching inputs:
Controller MicroLogix 1100
DC Inputs 0 through 3
You enable this feature with RSLogix 500 programming software. With an
open project:
1. Open the "Controller" folder.
2. Open the "I/O Configuration" folder.