i have a visa for espana (+1trans o5 schengen), type d, mult. valid from sep 15. 180 days. but on sep 23, i want to go to Portugal for a conference and return on sep 26. could i go without a visa for Portugal?
i do not think i need residence permit. i am chinese. merci

Your visa is valid only to transit through an other Schengen State on your way to Spain.

To go to Portugal, you need:

- either the residence permet the Spanish authorities are supposed to issue to you (but I doubt you would get it in time)

- or a specific visa for Portugal.