S7-300的模块机架（起物理支撑作用，无背板总线），西门子提供五种规格的导轨。
电源模块（PS）
将市电电压（AC120/230V）转换为DC24V，为CPU和24V直流负载电路（信号模块、传感器、执行器等）提供直流电源。输出电流有2A、5A、10A三种
正常：绿色LED灯亮
过载：绿色LED灯闪
短路：绿色LED灯暗（电压跌落，短路消失后自动恢复）
339021AA
339031AA
339051AA
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339210AA
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339220
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339250
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339306CA7
339310AA
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339420AX
3SE21000E
3SE21001B
3SE21001C
3SE21001D
3SE21001DV000AH3
671532BA020XB4
671532BA020XB5
671532BA810XB0
671532BA820XB0
671532BB000XB0
671533AA000XB0
671533AA010XB0
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671560AA010XA0
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671570AC000XA0
671570AC800XA0
671570AC810XA0
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671570AC830XA0
671570AD800XA0
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671570AF810XA0
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671570AF830XA0
671580AA010XA0
671580AD000XA0
671580AD010XA0
671583AD000XA0
671583AD010XA0
671740AA100AA0
67178H000AE0
3RV10111GA20
3RV10111HA10
3RV10111HA15
3RV10111HA20
3RV10111JA10
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3RV10111KA10
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3RV10210AA10
3RV10210AA15
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3RV10210CA10
3RV10210CA15
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3RV10210EA10
3RV10210EA15
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3RV10210GA10
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3RV10210HA10
3RV10210HA15
3RV10210JA10
3RV10210JA15
3RV10210KA10
3RV10210KA15
3RV10211AA10
3RV10211AA15
3RV10211BA10
3RV10211BA15
3RV10211CA10
