For some reasons, I can't install node-red-contrib-modbus into MAC. I tried to install using the command ofnpm install -g node-red-contrib-modbus. Then the message says that I don't have access permission
Hi @Lim Welcome to the community !!!1
I Guess you have posted the question directly in the topic header. Going forward please follow [Get involved : Node-RED] (Get involved : Node-RED) guidelines for better responses.
To answer you question:
If its an access permission, I would encourage you to contact your administrator for assistance. Anyways please refer to this link and follow the same node-red-contrib-modbus (node) - Node-RED
Why are you trying to install it globally? That is generally not the correct way.
Go into your .node-red folder (or wherever your flows file is) and run
npm install node-red-contrib-modbus
In future please don't post screenshots. Copy/paste the text here.