Siemens PLC功能 ，使用SCL语言编写，与pascal结构类似，完成了个从0-2^31-1的时间计数-this FB is only necessary for siemens sps the siemens sps timer counts from 0 to 2^31-1 and starts at 0 sfter overrun. this means that the bit 31 (the highest bit ) will never be used and th