Rockwell Automation 1746-INT4 Thermocouple/MV Isolated/ User Manual - Manual (Page 57)

57 Publication 1746-UM614B-EN-P - September 2007
Chapter
7
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.
Processor Basics 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.