Automationdirect.com DirectLOGIC DL205 Series User Manual page 121

Chapter 3: CPU Specifications and Operations
Initialization Process
1
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.
2
Initialization
3
Minimum Time
Maximum Time
4
Reading Inputs
The time required to read the input status for the input modules depends on which CPU you
5 are using and the number of input points in the base. The following table shows typical
update times required by the CPU.
6
Timing Factors
Overhead
Per input point
7
For example, the time required for a DL240 to read two 8-point input modules would be
8 calculated as follows, where NI is the total number of input points:
Formula
9
Time = 32µs + (12.3 x NI)
Example
10
Time = 32µs + (12.3 x 16)
Time = 228.8 µs
11
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.
12
13
14
A
B
C
D
3–30
DL205 User Manual, 4th Edition, Rev. B
DL230 DL240
1.6 Seconds 1.0 Seconds
3.6 Seconds 2.0 Seconds
DL230
64.0 µs 32.0 µs
6.0 µs 12.3 µs
DL250–1
1.2 Seconds
2.7 Seconds(w/ 2 exp. bases)
DL240 DL250–1
12.6 µs
2.5 µs
DL260
1.2 Seconds
3.7 Seconds (w/ 4 exp. bases)
DL260
12.6 µs
2.5 µs