Allen-Bradley SMC-50, User Manual

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Rockwell Automation Publication 1560F-UM001A-EN-P - June 2019 277
Using DeviceLogix Appendix G
Example 2: Wet Well Operation
This example demonstrates how you can use basic control logic for motor
control. It is assumed that a Digital I/O (150-SM4) option module is installed
in Port #8.
Figure 105 - Wet Well
The application consists of the discrete I/O that is listed in Table 79
Table 79 - Wet Well Discrete I/O
Example logic requirements:
• Start the motor when the High Level Sensor is ON.
• Stop the motor when all the level sensors are OFF.
• Annunciate a Sensor Fault condition and Stop the controller when any
of these conditions exist:
– The Low Level sensor is OFF when either the High Level or Critical
High Level sensors are ON
– The High Level sensor is OFF when the Critical High Level sensor is
ON
Type Location of I/O Name Description
Inputs
Port #8 Input #2 Critical High Level sensor
Indicates a critically high level. It is normally a backup to
the High Level sensor and is also used to detect whether
the High Level sensor is faulty.
Port #8 Input #3 High Level sensor
Indicates the well is at a high level and it is time to start
pumping using the controller.
Port #8 Input #4 Low Level sensor
When OFF, it is used to indicate that the well is empty
(as long as the High and Critical High Level sensors are
also OFF). The controller stops operating (end of
pumping cycle).
Outputs
Port #8 Aux #1 Sensor Failure pilot light Indicates that there is a problem with either the High
Level or Low Level sensors
Port #8 Aux #2 Critical Level Pilot light Indicates that the Critical Level Sensor is active.
No External Wiring Start Start signal to the SMC-50 control module.
No External Wiring Stop Stop signal to the SMC-50 control module.
Outflow
Inflow
Critical High Level Sensor
High Level Sensor
Low Level Sensor