As S7-300/400 series PLC(Programmable Logic Controller) is node controller based on field bus net,it is difficult to develop the communication software on Lab Windows/CVI platform for its privacy of communication protocol.
An OPC(OLE for Process Control) server is built on local PC,and then a Profibus-DP net is created using Simatic NET software to realize the point-to-point connections between OPC server and inputs/outputs of S7-300/400.Steps to configure PC station,master/slave system and connections between PC and PLC are presented in detail.
A recognition problem in converting linear programming to network flow models
A routing in a network assigns to each ordered pair of nodes a fixed path.
When either a node or a link in a fault-tolerant network fails, the communication from one node to another using this faulty element must be sent via one or more intermediate nodes along a sequence of paths determined by this routing.
An important and practical problem is how to choose a routing in the network such that inter-mediate nodes to ensure communication are small for any fault-set.
The result shows that most inverse network optimization problems with l∞ objective function can be solved in the polynomial time.
In this paper for the two-dimensional diffusion equation, the net region is divided into bands, a special kind of block.
Some of them including the existence problem, minimax problem, net representation, bend minimization, area minimization, placement problem, routing problem, etc.
A series of Petri net-based definitions were formulated for describing four types of structural errors in a rule-based system (RBS), including inconsistency, incompleteness, redundancy and circularity.
A marked ω-Petri net model of acyclic RBS was constructed.
The results showed that the diurnal course of net photosynthetic rate displayed a two-peak pattern, that of stomatal conductance displayed a hollow pattern, and that of transpiration rate displayed a signal-peak pattern.
The system is controlled by three computers which can communicate with each others by net work.
A net work like defect structure is concluded to determine the pinning character and the ability of Nb3Sn to carry a high transport current.
A simplified model is developed to reduce the storage space required for the system matrixA which represents the generators field, amortisseur windings, voltage regulators, speed governers, and the interconnected power net work.
In the periphery of the edematous white matter they were distributed in reticular fashion, which might indicate that they are present in the net work of cell processes.
The total oxygen uptake during the work averaged 2.35 l, the net oxygen recovery was 4.891, while the net work efficiency was 19.3 %.