ABB 5SHY3545L0002 3BHE009681R0101分散控制系统
控制字寄存器和定时器的I/O地址。控制字寄存器是只读的。计时器状态信息可从“读回”命令获得（参见第59页的“读取”部分）。计时器0、1和2这三个计时器在功能上是等效的。因此，将仅描述单个计时器。图4-5是计时器的框图。每个计时器功能独立。虽然控制字显示在计时器框图中，但它不是计时器的一部分，但其内容直接影响计时器的功能。如图4-5所示，当锁存时，状态寄存器包含控制字寄存器的当前内容以及输出和加载计数标志的当前状态（状态字可通过读回命令获得，请参阅第59页的“读取”部分）。计时器标记为TE（计时器元件）。它是一个16位同步可预置递减计数器。
the I/O addresses of the Control Word Register and Timers. The Control Word Register is write only. The Timer status information can be obtained from the Read-Back command (see the “Reading” section on page 59).The three Timers, Timer 0, 1, and 2, are functionally equivalent. Therefore, only a single Timer will be described. Figure 4-5 is a block diagram of a Timer. Each Timer is functionally independent. Although the Control Word is shown in the Timer block diagram, it is not a part of the Timer, but its contents directly affect how the Timer functions. The status register, as shown in Figure 4-5, when latched, contains the present contents of the Control Word Register and the present state of the output and load count flag (The Status Word is available via the Read-Back command, see the “Reading” section on page 59). The Timer is labeled TE (Timer Element). It is a 16-bit synchronous presettable down counter.
