1. Programmable logic controllers: Principles and applications;Webb,2002
2. Programmable logic controllers: Industrial control;Kamel,2013
3. Boggs MS, Fulton TL, Hausman S, McNabb G, McNutt A, Stimmel SW. Inventors; Siemens Energy, Automation Inc, assignee. Programmable logic controller customized function call method, system and apparatus. United States patent US 6, 904, 471. 2005.
4. Siemens: Simatic S7-200 programmable controller system manual;Siemens,2004
5. Reconciling programmable logic controllers (PLCs) with mechatronics control software;Auslander,1996