One thing every new Simcenter Amesim user struggles with is coordinate systems in Simcenter Amesim. Learning where to quickly find information about these coordinate systems is important. Almost every Simcenter Amesim component has ports. Ports are where inputs are applied and outputs received and each has at least one coordinate system and usually more. When you build a sketch you can access the "External Variables" view of any component by right-clicking on it. Here below are several.
At each of the ports you have inputs with red arrows and outputs with green arrows. Inputs are required to be satisfied by what you connect the ports to and outputs may or may not be used by whatever component the port is connected. In the rotary mechanical domain lay your right thumb in the direction of the arrow and follow the ‘right hand rule’. This will give you positive direction for the quantity of interest. In all cases, the arrow points to the positive direction. And yes, for the components shown above there are at least two coordinate systems per port as is the case of the planetary gearbox above. It also has as part of its symbol a plus sign and an arrow. If the component contains such a symbol it is the positive direction for a parameter coordinate system.