User Manual Instruction Manual

39 Publication 1746-UM009B-EN-P - September 2007

Chapter

Write Ladder Logic

This chapter presents these programming examples.

• Retentive and non-retentive programming

• Detect an out-of-range input

• Scale analog inputs and detect an out-of-range condition

• Scale analog outputs

• Scale offsets when > 32,767 or < –32,768

• Scale and range-check analog inputs and outputs

• PID xontrol with analog I/O scaling

Retentive and Non-retentive

Programming

The processor’s automatic response for scanning the I/O image table

is described below.

IMPORTANT

We present programming examples for instructional purposes

only. Because of the many variables and requirements

associated with any application, Rockwell Automation cannot

assume responsibility or liability for actual use based on these

examples.

Processor Automatic Response

Conditions Processor Response

• Mode is switched to Program

• Power is turned OFF

Retains the last values in the I/O image

table

• Mode is switched to Run

• Power is turned ON

Transfers output image data to the module

and input image data from the module

• Processor detects a minor fault Resets analog outputs to zero, but retains

output image values

• Fault condition is corrected Transfers output image data to the module