IDEC SmartAXIS Touch FT1A Series, User Manual

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6 Important Notes
20-52
SmartAXIS Touch User’s Manual
6.3 Write Delay
In a script of HMI function the writing process to external device addresses is performed at the end of a script, so it
may not operate correctly due to the write delay.
Example where write delay occurs
Initial value of D100 is 0.
Since the write destination of 1000 in first line is the external device address, the value is not reflected immediately,
and the value of D100 is still 0 when the second line is executed.
Therefore, the value where 5000 is added to 0 (value of D100) would be written to D200 in second line.
The value of D100 will be 1000 and the value of D200 will be 5000 when above script is executed.
There are 2 countermeasures for cases like this.
●
Not using the device cache
Write delay does not occur when writing to the internal device, so the calculation is performed only in the internal
device, and only the result will be written to the external device address.
●
Using the device cache
Problems with the write delay to the external device address can be avoided by caching the value of the external
device address into the internal memory. To use the device cache, setup as follows in WindO/I-NV3.
1
On the Configuration tab, in the System Setup group, click Project .
The Project Settings dialog box is displayed.
2
In the System tab, click Advanced .
[D 100] = 1000;
[D 200] = [D 100] + 5000;
[LDR 0] = 1000;
[LDR 0] = [LDR 0] + 5000;
[D 200] = [LDR 0];