Publication 1766-RM001A-EN-P - October 2008
I/O Configuration 33
Latching Inputs
Converting Analog Output Value to Actual Output Voltage
Analog outputs convert voltage signals into 12-bit values. To determine an
approximate voltage that an output value represents, use the equation
shown.
For example, if an input value of 3000 is in the output image, the
calculated value is as follows:
The MicroLogix 1400 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:
Enable this feature using RSLogix 500/RSLogix Micro. With an open
project:
1. Open the Controller folder.
2. Open the I/O Configuration folder.
3. Open slot 0 (controller).
4. Select the Embedded I/O Configuration tab.
5. Select the mask bits for the inputs that you want to operate as
latching inputs.
6. Select the state for the latching inputs. The controller can detect
both “on” (rising edge) and “off” (falling edge) pulses, depending
upon the configuration selected in the programming software.
The following information is provided for a controller looking for an “on”
pulse. When an external signal is detected “on”, the controller “latches”
this event. In general, at the next input scan following this event, the
input image point is turned “on” and remains “on” for the next controller
scan. It is then set to “off” at the next input scan. The following figures
help demonstrate this.
Controller MicroLogix 1400
DC Inputs 0…11
10V
4095
----------- -
outputvalu e× ou tputvoltage V()=
10V
4095
----------- -
3000× 7.326 V()=
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
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