Channel Scanning Sequence - Automation Direct DL405 User Manual

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.
Channel The F4–16DA–1 module allows you to update the channels in any order. Your
control program determines which channels get updated on any given scan. The
Scanning
Sequence channels are organized as two banks of outputs, eight channels each. A typical
ladder program will update one channel in each bank, or two channels per CPU
scan. So, all sixteen channels can be updated every eight scans. With a DL440 or
DL450 CPU, you can use Immediate instructions to update all sixteen channels in
the same scan (we'll show you how to do this later).
F4–16DA–1 16-Ch. Analog Current Output
Scan
Read inputs
Execute Application Program
Calculate the data
Write data
Write to outputs
Channel 1
Scan N
Channel 9
Channel 2
Scan N+1
Channel 10
Channel 3
Scan N+2
Channel 11
Channel 4
Scan N+3
Channel 12
Channel 5
Scan N+4
Channel 13
Channel 6
Scan N+5
Channel 14
Channel 7
Scan N+6
Channel 15
Channel 8
Scan N+7
Channel 16
Channel 1
Scan N+8
Channel 9
16–7