Personally I just used photoshop to make our teams schematics. I don't know if you have access to it but it was the easiest thing for me to use since I had used it before and I didn't feel like learning a whole new software
Basically I took jpeg pictures of each component jaguar, crio etc using vista's snipping tool. I took them from the power diagram in the control system section of the usfirst website Then I put them in photoshop each one as a layer. Then I moved them around til I liked it and drew in the wires.