In practice, the Controller selects the primary LC module to communicate with the
field devices by setting its controlreg true. The Modbus interface program, which
has been testing this digital, begins to communicate with the field devices.
After the primary LC has successfully made each of the configured transactions
once, it signals back to the Controller via the ExecutedOnceReg. If communication
is successful, the interface program updates the hardware watchdog timer. If
communication fails, the timer expires and the Controller, which is monitoring the
watchdog, sets the primary LC module’s controlreg false and the secondary
module’s controlreg true.
The secondary LC module then takes over communicating with the field devices.
5-6. Bumpless Switchover
U3-1050 5-4 11/98
Westinghouse Proprietary Class 2C
5-6. Bumpless Switchover
The danger exists that during the switchover from either LC module to its redundant
partner, bad data could be transferred to either the Controller or to the field devices.
This possibility is overcome by two techniques, one for each data transfer direction.
Controller to Field Devices
For data going from the Controller to the field devices, the algorithms SLCAOUT
and SLCDOUT are doubled for the second LC module.

实际上，控制器选择主LC模块与控制器通信
通过将其controlreg设置为true来现场设备。Modbus接口程序
一直在测试这个数字，开始与现场设备通信。
主LC成功完成每个配置的事务后
一次，它通过ExecuteOnCereg向控制器发回信号。如果通信
如果成功，接口程序将更新硬件看门狗定时器。如果
通信失败，计时器过期，控制器监控
watchdog，将主LC模块的controlreg设置为false，将辅助LC模块的controlreg设置为false
这是真的。
然后，辅助LC模块接管与现场设备的通信。
5-6. 无颠簸切换
U3-1050 5-4 11/98
西屋专有2C级
5-6. 无颠簸切换
在从任一LC模块切换到其冗余模块的过程中，存在以下危险：
合作伙伴，坏数据可能会传输到控制器或现场设备。
这种可能性可以通过两种技术来克服，每个数据传输方向一种。
控制器到现场设备
对于从控制器传输到现场设备的数据，算法是SLCAOUT
对于第二个LC模块，SLCDOUT增加了一倍。