YOKOGAWA STARDOM FCN-500, Engineering Manual

Page: 28 / 226

<2. Basic Design and Function Design>
20
TI 34P02K35-02E Jun. 6, 2018-00
● Behavior of Retain Data in FCN/FCJ Start Mode
Performing offline download to FCN-500 or FCN-RTU from Logic Designer stops
control on the FCN-500 or FCN-RTU. However, as power supply is not
interrupted, retain data, even if resident in volatile memory, retain their data. As
such, the behavior of retain data after data download in the FCN/FCJ start mode
is the same regardless of whether retain data is resident in volatile or non-volatile
memory.
1. If FCN/FCJ is warm started
1.1 If there is no change in retain data area
If there is no change in the retain data area, control is started using retain data
values current before offline download, even if the control application has been
changed.
1.2 If retain data structure has been changed
If the number or data type of retain data has been changed so that the retain
data structure is modified, retain data in the memory can no longer be used.
SEE ALSO Point 1 of TIP below
In this case, all retentive variables are first initialized to their initial values. If
retain data has been previously saved to the flash memory, control is restarted
using that data.
SEE ALSO Point 2 of TIP below
If no retain data is saved on the system card, the FCN-500 or FCN-RTU is
rebooted with initial values for retentive variables.