AutomationDirect DL205 - Output Channel Update Sequence for a DL230 CPU (Multiplexing); Output Channel Update Sequence for DL240, DL250-1, and DL260 Cpus (Pointer Method)

DL205 Analog Manual, 7th Edition Rev. D
14-9
Chapter 14: F2-4AD2DA 4-Ch. In / 2-Ch. Out Analog Combination
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Output Channel Update Sequence for a DL230 CPU (Multiplexing)
If a DL230 CPU is used, only one channel of data can be sent to the output module on each
scan. Since there are two channels, it can take two scans to update both channels. However, if
only one channel is being used, then that channel can be updated on every scan.
Output Channel Update Sequence for DL240, DL250-1, and DL260 CPUs
(Pointer Method)
If either a DL240, a DL250-1 or a DL260 CPU is used with the pointer method, both channels
can be updated on every scan. This is because the three CPUs support special V-memory
locations that are used to manage the data transfer. This is discussed in more detail in the next
section on Writing the Control Program.
Channel1
Channel2
Channel1
Channel2
Channel1
Scan N
Calculatethe data
Write data
Read inputs
ExecuteApplication Program
Scan N+1
Scan N+2
Scan N+3
Scan N+4
Scan
Writetooutputs
System With
DL230 CPU
Channel1,2
Channel1,2
Channel1,2
Channel1,2
Channel1,2
Scan N
Calculatethe data
Write data
Read inputs
ExecuteApplication Program
Scan N+1
Scan N+2
Scan N+3
Scan N+4
Scan
Writetooutputs
System With
DL240/250-- 1/260
CPU