参考一下网址，不过根据描述，extreme型PLC是经过特殊处理的允许结露，恶劣气体侵蚀，这意思是普通的可能不行
http://www.automation.siemens.com/mcms/topics/en/siplus/extreme/Pages/default.aspx

http://www.automation.siemens.com/mcms/topics/en/siplus/extreme/Pages/default.aspx?tabcardname=products

S7-1200
Product Information
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Overview
Technical specifications
Overview

The controller for use in the toughest environmental conditions
Features an extended temperature range of -25 °C to +55/70 °C
Suitable for medial exposure (harmful gas atmosphere)
Condensation permissible
Features the proven PLC technology of the S7-1200
Easy to handle, program, maintain, and service
The replacement for expensive custom solutions
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