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Fromto和Pin pair的含义不完全一致：: `# n2 e# e, k2 e; M8 p
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The Difference Between From-Tos and Pin Pairs % w; r9 b& T$ ]6 E) L
" ?) J) M X5 n4 n1 U* h( ^4 EOften times, from-to relationships can be confused with pin pair designations. To better understand these separate design attributes, please refer to the following definitions:
: B6 s0 a* y; Y: S •Net line ordering/from-tos - Ordered, physical pairings of component pins that instruct the router where to etch from and to when creating physical transmission lines (traces).6 ?7 @0 H( l) G5 \; o: m
•Pin pairs - Electrical pairings of component pins that are created for the purpose of defining electrical relationships between component pins in the form of constraints.( `5 q- I4 j7 F( o/ E4 X! F* T' T
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只有定义了Pin pairs，才会生成虚拟节点(Virtual Pins)，也就是你说的T点——d，这样CES才能识别同一trace中的不同区段，才会显示各区段的长度；9 |" \& `5 ?3 E7 r+ x# y8 t
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单纯定义From-to的话，即使实际走线是拓扑结构，CES只识别两个pin之间的trace长度，而忽略拓扑。 |
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发表于 2013-6-20 14:03
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