UML drawing tools

1. tools based on the script

http://www.websequencediagrams.com/

UMLet 12.1

My best two recommendations right now would be: yUML and PlantUML (http://www.plantuml.com/plantuml/form)

If you need something more complex and integrated with Eclipse try TextUML

2. Examples of PlantUML 

a) 

(*)--> "2D calibration"
--> "3D calibration"
--> "Z calibration & Adjust belt levels"
--> "Learn"
if "3DS Optics" then
-->[true] "Check belt vibration (without wafer)"
--> "Check belt vibration (with wafer)"
else
--> "Check belt vibration (with wafer)"
endif

--> "0-90 deg Calibration (Update Z Calibration)"
--> "5-PT TTV compensation"
--> "Thickness compensation"
--> "Check repeatability"
--> (*)

b) 

Host --> "Vision Appl": Start auto run mode
"Vision Appl"-->"Vision System": Start OTF mode
"Vision Appl" --> Host: Auto run mode enabled
"Wafer" --> "Vision System": Wafer is comming
"Vision System"-->"Vision Appl": Start sensor detected
"Vision Appl"-->"Vision System": Start OTF trigger
"Vision System"-->"Vision Appl": Trigger points are triggered
"Vision Appl"-->"Vision Algorithm": Do construction & Inspection
"Vision Appl"-->"Vision System": Stop OTF trigger
"Vision Algorithm"-->"Vision Appl": Construction & Inspection done
"Vision Appl" --> Host: Wafer inspection done
Host --> "Vision Appl": Get inspection result
"Vision Appl" --> Host: Send inspection result

Host --> "Vision Appl": Stop auto run mode
"Vision Appl"-->"Vision System": Stop auto run mode
"Vision Appl" --> Host: Stop auto run mode ok