AutomationDirect DL205 - Module Operation; Channel Update Sequence for a DL230 CPU (Multiplexing)

DL205 Analog Manual, 7th Edition Rev. D
12-7
Chapter 12: F2-02DAS-1, 4-20mA 2-Channel Analog Current Output
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Module Operation
Before beginning to write the control program, it is important to take a few minutes to under-
stand how the module processes the analog signals.
Channel Update Sequence for a DL230 CPU (Multiplexing)
If a multiplexing program is being used, only one channel of data can be sent to the output
module on each scan. The module refreshes both field devices on each scan, but only new data
can be read by the CPU at the rate of one channel per scan. Since there are two channels, it
can take two scans to update both channels. However, if only one channel is being used, that
channel will be updated on every scan. The multiplexing method can also be used for the
DL240, DL250-1, and DL260 CPUs.
Channel 1
Channel 2
Channel 1
Channel 2
Channel 1
Scan N
Calculatethe data
Writedata
Read inputs
ExecuteApplic ationProgram
Scan N+1
Scan N+2
Scan N+3
Scan N+4
Scan
Writeto outputs
System Using
Multiplex
Method
(DL230)