Channel Scanning Sequence - Automation Direct DL405 User Manual

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F4–04DAS–1 4-Channel Isolated 4–20mA Output
Channel
Scanning
Sequence
Before you begin writing the control program, it is important to take a few minutes to
understand how the module processes and represents the analog signals.
The F4–04DAS–1 module allows you to update the channels in any order. Your
control program determines which channel gets updated on any given scan by
using two binary encoded output points. With a DL440 or DL450 CPU, you can use
immediate instructions to update all four channels in the same scan (we will show
you how to do this later).
Scan
Read inputs
Execute Application Program
Calculate the data
Write data
Write to outputs
Scan N Channel 1
Scan N+1 Channel 2
Scan N+2 Channel 3
Scan N+3 Channel 4
Scan N+4 Channel 1