Sequencing The Channel Updates - Automation Direct DL405 User Manual

16–14
F4–16DA–1 16-Ch. Analog Current Output
Sending Data to
One Channel,
DL430
4 4 4
430 440 450
Sequencing
the Channel
Updates
SP1
Select Channel
Enable Outputs
The next four example programs show you how to send digital values to the module
when you have more than one channel. These examples automatically update all
sixteen channels over eight scans. Channel updates occur in pairs, such as
channels 1 and 9, channels 2 and 10, and so on. This method uses the same binary
code for the channel select bits of both groups of outputs, simplifying the programs.
You may recall we stated earlier you could update all sixteen channels in the same
scan. That's true, you can do that if you have a DL440/450 CPU; however, this can
increase the scan time and you may not always need to update all sixteen channels
on every scan. We show you how to do this later in this chapter.
The first two sequencing examples are fairly simple and will work in most situations.
We recommend these for new users. They use control relays C1 through C8 as
index numbers corresponding to the pair of channels updated on any particular
scan. At the end of each scan, only one control relay C1 through C8 is on. On each
subsequent scan, the next control relay energizes. The channel sequencing
automatically begins with channels 1 and 9 on the first scan, or after any disruption
in the logic.
The last 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 words to the module.
The LD instruction loads the data for channel 1 into
LD
the accumulator. Since SP1 is used, this rung
V3001
automatically executes every scan. You could also
use an X, C, etc. permissive contact.
The BIN instruction converts the accumulator data
BIN
to binary (you must omit this step if you've already
converted the data elsewhere).
The ANDD instruction masks off the channel select
ANDD
bits to prevent an accidental channel selection.
KFFF
The OUT instruction sends the data to the module. Our
example starts with V40501, but the actual value
OUT
depends on the location of the module in your
V40501
application.
Y36
Turn Y36, Y35, and Y34 off to update Channel 1.
RST
Y36 Y35
Off Off
Y35
Off Off
Off On
RST
Off On
On Off
Y34
On Off
On On
RST
On On
Y37
Turn on Y37 to enable all eight output channels of
SET
the first bank.
Y57
Turn off Y57 to disable the second bank of
RST
channels, 9 through 16.
Y34 Channel
Off Ch. 1
On Ch. 2
Off Ch. 3
On Ch. 4
Off Ch. 5
On Ch. 6
Off Ch. 7
On Ch. 8