没有必要初始化的~
参考一下：
http://www.google.cn/search?client=aff-os-360se&ie=utf-8&oe=UTF-8&hl=zh-CN&q=s7300PID%E8%87%AA%E6%95%B4%E5%AE%9A%E5%8A%9F%E8%83%BD

http://support.automation.siemens.com/CN/llisapi.dll?func=cslib.csinfo&lang=zh&siteid=cseus&objid=18652438

s7300PID中文说明：
http://ishare.iask.sina.com.cn/f/3022075.html
s7300PID例：
http://ishare.iask.sina.com.cn/f/3022075.html
S7-300 FB41 PID参数如何设置?:
http://plc.jdzj.com/article/2009-2-6/3533-1.htm