Can a pinned piece still act as a cannon's screen?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws for movement, checkmate and both repetition rulings: a side that forces a repetition by perpetual check or perpetual chase loses rather than drawing. The chase half has not been validated against the official casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it before publishing.
Direct answer
Yes. Being pinned only limits where a piece can move; it does nothing to whether it can still serve as a screen, which is purely a matter of standing on the right point. A piece pinned between the two generals, or pinned by an enemy chariot, screens a cannon exactly as well as any other piece would.
Why this makes sense once you separate the two roles
A screen's job has nothing to do with mobility, it is simply about occupying a specific point on a line. A pinned piece is, if anything, an unusually reliable screen, because its own side may not be able to move it out of the way even when doing so would help them.
Where this comes up in practice
A piece standing alone between the two generals is a common case. It may not leave that file, but it also stands on a rank, and a cannon on that rank still fires straight over it exactly as if it were free. The pin restricts the piece's owner, not the cannon using it.
Related questions
Does the pinned piece's owner benefit from this at all?
No, the screen works the same regardless of whose piece it is or whether that side wants it there.
Can a pinned piece be captured while acting as a screen?
Yes, exactly like any other piece, being pinned does not protect it from capture.
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