注意特殊值- 0，正如清单4中的用法一样，它将测试是否可以将某个信号发送到进程。
Note that the special value -0, as used in Listing 4 above, tests whether a signal could be sent to a process.
同步测试中两任务间在一个循环中来回发送信号实现同步。
For synchronization testing, in a cycle between two tasks, the synchronization was realized through sending signal back and forth.
本地主控机通过RS485总线向现场信号采集设备发送控制指令并接收采集的测试数据，从而实现对rs485总线通信的控制。
The local controller sends steering order to field signal-acquisition equipments and receives test data from RS485 bus, thereby communication control of RS485 bus was realized.
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