Study on decomposition for LD-based complicated dependence analysis

ZHAO Ying， YAN Yi
（Institute of Software and Intelligent Technology， Hangzhou Dianzi University， Hangzhou 310018， China）

Abstract： Dependence analysis is an important method of testing，understanding，maintaining program and parallel compiling. Aiming that the parallelism of ladder diagram（LD）is difficult to identify，the dependence relations among the rungs were established from the data and control aspects. A method was proposed to decompose dependence relations and the examples were given. The research results show that the method can identify the concurrent rungs，shorten the scan time and improve the response speed of the system.
Key words： programmable logic controller（PLC）；ladder diagram；data dependence；control dependence