Proper Arrow Directions for Off Page Connectors / Symbols...

Question

Good day everyone,

As I understand it, there are two kinds of objects that can be used on a schematic to indicate that the Net to which they are attached is connected to a location elsewhere on the schematic (maybe the same or a different sheet). The reason is to allow the flow of the schematic to be clear and / or to allow a signal path to be continued on another page.

I have heard / seen these objects referred to as off page connectors (or symbols), ports, etc. I am guessing that they may (or may not?) have different names depending on whether or not the signal appears elsewhere on the same sheet. In that case, I have often seen the Net line simply end, with a little alias or name at the dead end that can be found elsewhere on the same sheet.

The real question I have is this: I am trying to understand the correct direction of the arrow to select for the off page (or on page for that matter) connector symbol. I gather that, for logic signals, gate outputs and the like use the arrow direction arranged such that the outputs are pointing to some other gate's input. That other gate input has a corresponding incoming arrow. But what if there is a control voltage / current to be applied to an external load and there are two wires, a send and return. I can imagine that there would be one arrow out (the outgoing driving current (conventional)) and one arrow point back in (the returning current (conventional)). But, I wonder if both of these arrows should point outward (towards the load), since they work together to act as a 'data signal output' (and what if the output pair is an AC voltage?). In summary, what is a good, consistent, standard practice to assign directional arrows for on page / off page connector symbols? Do I follow the conventional current, or the flow of data? Or does it depend? I know there are bidirectional arrows available.

This is my first question. I do believe I searched thoroughly enough to be sure it is not a redundant question.

Thank you very much for reading! Any advice will be very much appreciated! Best,
Eric

Answer 1

An off-page connector for an output should be drawn as an out arrow even if the output sinks current. Here's an example.

Block diagram perspective:

Detailed perspective (contents of the green block):

Answer 2

The way off page symbols are used is purely for documentation, and has no magic electrical significance. Documentation is intended to convey unambiguous information, from your past self to your future self, and between you and others.

That means
a) find out what the convention is for your drawing package, and field of application
b) use that convention

unless of course it is only you who will ever see these drawings, in which case you can make up any convention that is consistent with the way the drawing package works. Make sure you remember what convention you came up with, it will save you confusion when you come to read your circuits later.