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Processor Basics
57
Ladder Programming Examples
Earlier chapters explained how configuration words define channel
operation. This chapter shows examples of ladder logic that you write
to:
• load configurations into the output image file to be scanned to
the module.
• change the configuration of a channel.
• verify that the change in configuration occurred.
• process a channel input value with a PID instruction.
• monitor channel status.
We start with some basic concepts of the SLC processor.
For the examples in this chapter, we have assigned the module to slot
3 and have addressed ladder logic files in the SLC processor as
follows:
• Configurations are stored in words 0...3 of integer file #N10
• Configurations are scanned to the module from output image
words O:3.0 through O:3.3
• Channel data words and channel status words are scanned from
the module into input image words I:3.0 through I:3.3 and
I:3.4 through I:3.7, respectively
During the program scan, the SLC processor follows the ladder logic
instructions that you create to perform such functions as:
• copy or move configurations from integer file #N10 to the
output image file to be scanned to the module during the next
I/O scan.
• verify a change in configuration by comparing the channel status
word with the channel configuration word for equality.
• examine channel status bits to see if the module flagged a fault
condition.
• autocalibrate a channel by cycling the channel enable bit on and
off.
Chapter
Publication 1746-UM614B-EN-P - September 2007
7
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