Sensors (Digital Or Analog); Actuators; Creating The Application Program; Logic And Instructions - Allen-Bradley 1756-L7 Series Reference Manual

Creating the Application
Program
Allen-Bradley Motors
• Matrix- or table form of stepped conditions and the actuators to be
controlled, including the sequence and timing diagrams
• Definition of marginal conditions, for example, operating modes,
EMERGENCY STOP and others
The I/O-portion of the specification must contain the analysis of field circuits,
that is, the type of sensors and actuators.

Sensors (digital or analog)

• Signal in standard operation (dormant current principle for digital sensors,
sensors OFF means no signal)
• Determination of redundancies required for SIL levels
• Discrepancy monitoring and visualization, including the user's diagnostic
logic

Actuators

• Position and activation in standard operation (normally OFF)
• Safe reaction or positioning when switching OFF
• Discrepancy monitoring and visualization, including the user's diagnostic
logic
Consider the following when developing the application program logic.

Logic and Instructions

The logic and instructions used in programming the application must be:
• easy to understand.
• easy to trace.
• easy to change.
• easy to test.
• well-documented.
Rockwell Automation Publication 1756-RM001I-EN-P - May 2012
Requirements for Application Development Chapter 7
81