ABB 5SHX0660F0001 3BHB003387R0101端子模块
标记为OLM和OLL的块是8位输出锁存器（OL）。下标M和L表示最高有效字节和最低有效字节。这些锁存器通常跟踪TE，但当被命令时，将锁存并保持当前计数，直到CPU读取计数。当读取锁存计数时，OL寄存器将继续跟踪TE。读取OL寄存器时，必须执行两次8位访问以检索计时器的完整16位值，因为一次仅启用一个锁存器。TE无法读取；从OL寄存器读取计数。有两个8位寄存器，分别标记为TRM和TRL（定时器寄存器）。下标M和L表示最高有效字节和最低有效字节。当一个新的计数被写入计时器时，该计数被加载到TR中，然后被传送到TE。控制逻辑允许一次写入一个8位TR寄存器。必须执行两次8位写入才能加载完整的16位计数值。两个TR字节同时传输到TE。用户不能直接写入TE，计数被写入TR寄存器，然后锁存到TE。
The blocks labeled OLM and OLL are 8-bit Output Latches (OL). The subscripts M and L stand for Most Significant byte and Least Significant byte. These latches usually track the TE, but when commanded will latch and hold the present count until the CPU reads the count. When the latched count is read, the OL registers will continue to track the TE. When reading the OL registers, two 8-bit accesses must be performed to retrieve the complete 16-bit value of the Timer as only one latch at a time is enabled. The TE cannot be read; the count is read from the OL registers.There are two 8-bit registers labeled TRM and TRL (Timer Register). The subscripts M and L stand for Most Significant byte and Least Significant byte. When a new count is written to the Timer, the count is loaded into the TR and later transferred to the TE. The Control logic lets one 8-bit TR register be written to at a time. Two 8-bit writes must be performed to load a complete 16-bit count value. Both TR bytes are transferred to the TE at the same time. The TE cannot be directly written to by the user, the count is written to the TR registers, then latched to the TE.
