[{"title":"( 2 个子文件 640KB ) RS485上下拉电阻选择及计算,匹配电阻计算","children":[{"title":"RS485偏置电阻和匹配电阻计算.doc <span style='color:#111;'> 102.00KB </span>","children":null,"spread":false},{"title":"详解RS-485上下拉电阻选择.pdf <span style='color:#111;'> 615.27KB </span>","children":null,"spread":false}],"spread":true}]