PERIPHERAL EQUIPMENT FOR PROGRAMMABLE CONTROLLER, METHOD FOR CONTROLLING COMMUNICATION BETWEEN PERIPHERAL EQUIPMENT AND PROGRAMMABLE CONTROLLER AND COMPUTER READABLE RECORDING MEDIUM STORED WITH PROGRAM FOR CONTROLLING COMMUNICATION

摘要

PROBLEM TO BE SOLVED: To simultaneously execute communication with a personal computer(PC) connected by the same serial communication line from plural PC communication user programs without opening/closing the communication line in each process transition. SOLUTION: A serial communication line management part 13 judges whether a line opening request from each of PC communication programs 12a, 12b is an initial request or not and whether a line closing request from each of the programs 12a, 12b is a final request or not while referring to line open information stored in a serial communication line management information table 14, executes serial communication line opening processing and the registration of serial communication line information only by the initial line opening request, holds the serial communication line at an opened state up to the final line closing request and executes serial communication line closing processing only by the final line closing request. In the opened state of the communication line, serial communication with the PC 10 can be executed while referring to the serial communication line information registered in the table 14.