37 FUNCTIONS
37.8 Switching Safety Operation Mode
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37.8 Switching Safety Operation Mode
This section describes how to switch the safety operation mode.
Safety operation mode transition timing
The following table shows the timing at which safety operation mode switches.
The SIL2 Process CPU retains the safety operation mode status even when the CPU module is powered off or
is reset.
Safety operation mode switching direction Safety operation mode switch timing
TEST MODE SAFETY MODE When the CPU module is powered off and on or is reset after the safety
operation mode switching operation
SAFETY MODE TEST MODE At the safety operation mode switching operation
(1) After switching from TEST MODE to SAFETY MODE, the safety operation
mode will be SAFETY MODE (wait-for-restart). (The status will be wait-for-
restart until the CPU module is powered off or is reset.) An error occurs if
the SIL2 Process CPU is switched to the RUN state when in SAFETY
MODE (wait-for-restart).
(2) After switching the safety operation mode (TEST MODE SAFETY
MODE), the mode will switch to SAFETY MODE when the CPU module is
powered off and on or is reset.
(3) After switching the safety operation mode (SAFETY MODE TEST
MODE), the mode will switch to TEST MODE.
(1)
(2)
(3)
Safety operation mode
The CPU module is
powered off or being
reset.
TEST MODE
SAFETY MODE
(wait-for-restart)
The CPU module is
powered off or being
reset.
SAFETY MODE
TEST MODE
User operation
Power-on/Reset of the CPU
module
Writing programs and parameters
to the CPU module
Mode switching (other than RUN)
(TEST MODE → SAFETY MODE)
Power-off/Reset of the CPU
module
Power-on/Reset of the CPU
module
Mode switching
(SAFETY MODE → TEST MODE)
Factory default