YOKOGAWA STARDOM FCN-500, Engineering Manual

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<9. Advanced Engineering >
190
TI 34P02K35-02E May 31, 2017-00
9.1.12 Logic for Saving Retain Data
To save retain data on the on-board flash memory, change the system global
variable "GS_RETAIN_SV_SW” to TRUE.
This section describes some relevant programming precautions.
● Operation of GS_RETAIN_SV_SW
When a program or user sets GS_RETAIN_SV_SW to TRUE, the FCN-500 or FCN-
RTU begins saving retain data to the flash memory. When saving is completed, the
system automatically resets GS_RETAIN_SV_SW to FALSE.
The time required for saving retain data depends on the retain data size; the larger
the retain data size, the longer the required time.
Moreover, in order not to affect control, saving of retain data is carried out during the
idle time of the FCN-500 or FCN-RTU so the shorter the idle time, the longer the
required time for saving.
Therefore, saving of retain data may sometimes require several seconds.
IMPORTANT
After setting GS_RETAIN_SV_SW to TRUE to initiate saving of retain data, if a user
or an application then sets GS_RETAIN_SV_SW to FALSE before it is automatically
set to FALSE by the system upon completion of saving, saving will be aborted
immediately, leaving incomplete retain data on the system card.
● Programming Precautions
As described in the above precaution, after setting GS_RETAIN_SV_SW to TRUE, if
an application then sets GS_RETAIN_SV_SW to FALSE before it is automatically
set to FALSE by the system upon completion of saving, incomplete retain data will
be saved on the flash memory.
Note this precaution when creating applications for saving retain data.
• Application Example for Saving Retain Data
The application shown below gets the FCN/FCJ time as STRING-type data using
PAS_GETTIME2, and compares it against "0000" (00:00 hours). When a match
occurs, it sets GS_RETAIN_SV_SW to TRUE once.
As the application does not set GS_RETAIN_SV_SW to FALSE thereafter,
GS_RETAIN_SV_SW remains TRUE until it is set to FALSE by the system.