AutomationDirect DL205 - Initialization Process; Reading Inputs

DL205 User Manual, 4th Edition, Rev. D
3-30
Chapter 3: CPU Specifications and Operations
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Initialization Process
The CPU performs an initialization task once the system power is on. The initialization task
is performed once at power up, so it does not affect the scan time for the application program.
Reading Inputs
The time required to read the input status for the input modules depends on which CPU you
are using and the number of input points in the base. The following table shows typical update
times required by the CPU.
For example, the time required for a DL240 to read two 8-point input modules would be
calculated as follows, where NI is the total number of input points:
Formula
Time = 32µs + (12.3 x NI)
Example
Time = 32µs + (12.3 x 16)
Time = 228.8 µs
NOTE: This information provides the amount of time the CPU spends reading the input status from the
modules. Don’t confuse this with the I/O response time that was discussed earlier.
Timing Factors DL230 DL240 DL250–1 DL260
Overhead 64.0 µs 32.0 µs 12.6 µs 12.6 µs
Per input point 6.0 µs 12.3 µs 2.5 µs 2.5 µs
Initialization DL230 DL240 DL250–1 DL260
Minimum Time 1.6 Seconds 1.0 Seconds 1.2 Seconds 1.2 Seconds
Maximum Time 3.6 Seconds 2.0 Seconds 2.7 Seconds(w/ 2 exp. bases) 3.7 Seconds (w/ 4 exp. bases)