请问高人$A_DBD[0]是个什么东东?，似乎没见过这个变量啊!

查了手册，是个系统变量，还不建议使用为对时间敏感的信号？！

“System variables written from the PLC: $A_DBB, $A_DBW, $A_DBD

It is not recommended to use these system variables, written by the PLC for time-critical

signals, as in this case, the PLC cycle time is included in the total response time.

Nevertheless, it is an appropriate way for the PLC to influence the sequence or release of

the extended stop and retract function. However, linking-in PLC states in such a fashion

does make sense if these are exclusively input from the PLC (e.g. Emergency-Stop, reset

button, stop button)”

PLC如何写入这个信号啊？有对应的接口吗？