Description of Operation
Section
3-2
108
1: Longest operation cycle in the function block group comprising the loop
2:
is as follows depending on the total number of Field Ter CPU
Unit Ter Expanded CPU Unit Ter Node Ter
Send/Receive All Blocks (
is incremented by 1 at every 19 Terminals.)
Total number of nodes (Field Te CPU Unit
Te Expanded CPU Unit Te Node
Te Send/Receive All Blocks)
0 to 18
1
19 to 38
2
39 to 58
3
259 to 278
14
3:
is the smallest integer satisfying formula 1 below.
Formula 1:
{CY x (
+2) + 20}
T – 0.7 <
Note 1
+T (operation cycle) is further added when analog values are input and
output at AI/AO Terminals using a combination of Analog Input and Analog
Output Units for all Loop Control Units of version 2.00 or earlier. This value is
not added for Loop Control Units of version 2.50 or later.
Note 2
Calculate CY (cycle time) in 10 ms even if the actual cycle time is less than
10 ms.
Example
Cycle time of 15 ms, max. operation cycle of 0.2 seconds (200 ms), 50
function blocks (
= 3) exchanging data with the CPU Unit, A/D conversion
time = 8 ms, D/A conversion time = 8ms, Analog Input Unit and Analog
Output Units are separate units
= 0 as (15 x 5 + 20)
200 – 0.7 = -0.225 <
Therefore, in this example, the maximum I/O refresh cycle becomes as
follows:
8 ms + (4 x 15 ms) + (3 x 15 ms) + (2 x 200 ms) + (0 x 200 ms) + 20 ms +
8 ms = 541 ms
3-2-11-2
Minimum external I/O refresh cycle
The minimum external I/O refresh cycle is calculated as follows:
A/D conversion time + (1 x CY) + (
x CY) + (1.6 x T) + (
x T) + D/A
conversion time
where,
CY: Cycle time of the CPU Unit
T:
Max. operation time (
1)
