We address the formal verification of the control software of critical systems, i.e., ensuring the absence of design errors in a system with respect to requirements. Control systems are usually based on industrial controllers, also known as Programmable Logic Controllers (PLCs). A specific feature of a PLC is a scan cycle: 1) the inputs are read, 2) the PLC states change, and 3) the outputs are written. Therefore, in order to formally verify PLC, e.g., by model checking, it is necessary to describe the transition system taking into account this specificity and reason both in terms of state transitions within a cycle and in terms of larger state transitions according to the scan-cyclic semantics. We propose a formal PLC model as a hyperprocess transition system and temporal cycle-LTL logic based on LTL logic for formulating PLC property. A feature of the cycle-LTL logic is the possibility of viewing the scan cycle in two ways: as the effect of the environment (in particular, the control object) on the control system and as the effect of the control system on the environment. For both cases we introduce modified LTL temporal operators. We also define special modified LTL temporal operators to specify inside properties of scan cycles. We describe the translation of formulas of cycle-LTL into formulas of LTL, and prove its correctness. This implies the possibility ofmodel checking requirements expressed in logic cycle-LTL, by using well-known model checking tools with LTL as specification logic, e.g., Spin. We give the illustrative examples of requirements expressed in the cycle-LTL logic.

User-friendly formal specifications and verification of parallel and distributed systems from various subject fields, such as automatic control, telecommunications, business processes, are active research topics due to its practical significance. In this paper, we present methods for the development of verification-oriented domain-specific process ontologies which are used to describe parallel and distributed systems of subject fields. One of the advantages of such ontologies is their formal semantics which make possible formal verification of the described systems. Our method is based on the abstract verification-oriented process ontology. We use two methods of specialization of the abstract process ontology. The declarative method uses the specialization of the classes of the original ontology, introduction of new declarative classes, as well as use of new axioms system, which restrict the classes and relations of the abstract ontology. The constructive method uses semantic markup and pattern matching techniques to link sublect fields with classes of the abstract process ontology. We provide detailed ontological specifications for these techniques. Our methods preserve the formal semantics of the original process ontology and, therefore, the possibility of applying formal verification methods to the specialized process ontologies. We show that the constructive method is a refinement of the declarative method. The construction of ontology of the typical elements of automatic control systems illustrates our methods: we develop a declarative description of the classes and restrictions for the specialized ontology in the Prot´eg´e system in the OWL language using the deriving rules written in the SWRL language and we construct the system of semantic markup templates which implements typical elements of automatic control systems.