> Control systems engineers have been studying and documenting systems using Simulink-style block diagrams since at least the 1960s.
It dates to at least the 1940s with signal flow graphs (1) but from what I've heard, Shannon was working on fire control systems for the Navy and his work was classified. Some of that was famously published in A Mathematical Theory of Communication (2) where there are block diagrams for information systems, and Mason worked out Mason's Gain Rule/Formula in the early 1950s.
I would not be surprised if graphical representations date back to the 1920s/30s when abstracting electrical systems into things like circuit diagrams that ignore grounding were pretty common, or even earlier.
It dates to at least the 1940s with signal flow graphs (1) but from what I've heard, Shannon was working on fire control systems for the Navy and his work was classified. Some of that was famously published in A Mathematical Theory of Communication (2) where there are block diagrams for information systems, and Mason worked out Mason's Gain Rule/Formula in the early 1950s.
I would not be surprised if graphical representations date back to the 1920s/30s when abstracting electrical systems into things like circuit diagrams that ignore grounding were pretty common, or even earlier.
(1) https://en.wikipedia.org/wiki/Signal-flow_graph