Omron CS1W-LC001 Operation Manual page 128

Description of Operation
3-2-11-3 Restrictions on operation cycles of function blocks used for data
exchange with the CPU Unit
Example
110
In the case of the following function blocks that perform data exchange
with the CPU Unit, the operation cycle must satisfy formula 1 shown
below. If this formula is not satisfied, cases where data exchange with
the CPU Unit is not performed and data exchange processing does not
end when operation on those function blocks is executed may occur. If
this happens, the external I/O refresh cycle must be increased.
Target function blocks: Field Terminal
In most cases, the operation cycle of these function blocks must be at least
3.3 times the cycle time of the CPU Unit.
Formula 1: CY x (
where,
CY: Cycle time of CPU Unit
à is as follows depending on the total number of Field Terminals + CPU Unit
Terminals + Expanded CPU Unit Terminals + Node Terminals +
Send/Receive All Blocks ( Ã is incremented by 1 at every 19 Terminals.)
Total number of nodes (Field Terminal + CPU Unit
Terminal + Expanded CPU Unit Terminal + Node
Terminal + Send/Receive All Blocks)
In case of a cycle time of 25 ms, total number of Terminals 50 (Field Terminal
+ CPU Unit Terminal + Expanded CPU Unit Terminal + Node Terminal +
Send/Receive All Blocks), set the operation cycle to 0.2 seconds or more as
CY x (1+3) = 100 ms is less than operation cycle x 0.9 and the operation
cycle is greater than approx. 111 ms.
Note 1 Precautions When Using the Analog Input/Output Unit
The unit number set on the front panel of the unit must always match the unit
number setting of the Field Terminals.
When running of the Loop Control Unit is started using the Field Terminals,
the Loop Control Unit executes the following writing on the allocated CIO
area of the unit number specified by the Field Terminals.
CPU Unit Terminal
Expanded CPU Unit Terminal
Node Terminal
Á
+2) < Operation cycle of above function blocks x 0.9
0 to 18
19 to 38
39 to 58
259 to 278
Section 3-2
Á
1
2
3
14