Patent ID: 7953892

Claim:
A control system comprising a programmable logic controller to which an input apparatus and an output apparatus are connected, programmable display apparatuses, each of which displays control states of the input apparatus and the output apparatus caused by the programmable logic controller, and each of which gives a control instruction to the programmable logic controller, and each of the programmable display apparatuses communicating with the programmable controller via a designated network in a communication protocol designated to the programmable logic controller, a host computer provided ranking above the programmable display apparatus, the host computer accumulating data regarding the programmable logic controller by communicating with at least one of the programmable display apparatuses via a common network in a common communication protocol, wherein: the programmable display apparatus includes: a protocol converter ( 53 ) for converting the communication protocols used in the designated networks and the common communication protocol from one to the other; and a data delivery section ( 5 e ) for delivering to the host computer, a screen for displaying control states of the programmable logic controller, the screen being displayed by the programmable display apparatus when a preset delivery condition is satisfied, symbols as respective change elements, which are corresponded to addresses of the input and the output apparatus in the screen, and which are changed in accordance with data of the control instruction and output data from the programmable logic controller as a result of the control instruction data, and the control instruction data and the output data corresponding to the symbols, and the host computer includes: a database ( 27 ) for accumulating the screen, the symbols, and the control instruction data and the output data, which are thus delivered, sequentially in time sequence and per the programmable display apparatus; a database administrator ( 21 b ) for consecutively searching and displaying the screen, the symbols and the control instruction data and the output data accumulated in the database; a compiler ( 29 ) for converting, into an execution program executable for a terminal apparatus, the screen searched out by the searching means as requested by the terminal apparatus; and a public server section ( 30 ) for transmitting the execution program, the symbols, and the control instruction data and the output data to the terminal apparatus that executes the execution program, so as to change the symbols in the screen in accordance with the control instruction data and the output data.