Automation Direct DL405 User Manual page 253

Sequencing The next four example programs show you how to send digital values to the module
the Channel when you have more than one channel. These examples will automatically update
Updates all four channels over four scans.
The first two sequencing examples, examples 1 and 2, are fairly simple and will
work in almost all situations. We recommend these for new users. They use control
relays C1 through C4 as index numbers corresponding to the channel updated on
any particular scan. At the end of each scan, only one control relay C1 through C4 is
on. On each subsequent scan, the next control relay energizes. The channel
sequencing automatically begins with channel 1 on the first scan, or after any
disruption in the logic. You must use example 1 with DL430 CPUs. Either example
will work with DL440 or DL450 CPUs.
The next two examples, 3 and 4, are slightly more complex. However, they do not
depend on the use of control relays to provide channel sequencing. Instead, they
use function boxes to increment a channel pointer value in V-memory. Then, other
instructions perform bit manipulations to position the channel select bits properly in
the output word to the module. You must use example 3 with DL430 CPUs. Either
example will work with DL440 or DL450 CPUs.
In the last example, we show how you can update all four channels in the same scan
with DL440 and DL450 CPUs. However, this can increase the scan time and you
may not always need to update all four channels on every scan.
F4–04DA–1 Analog Current Output
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