| 摘要 |
PURPOSE:To simulate input/output even if a real process signal is not generated by always writing the state of a process in a storage device. CONSTITUTION:If an input request for a relay contact 8 is sent from an I/O request program 11 to an I/O-only program 10, the information is transmitted to a bus receiver 4 through a bus driver 3. The bus receiver 4 analyzes the address of the objective relay contact 8, reads the state of the contact 8 from its corresponding process I/O unit 6 and transfers the state of the process to the I/O-only program 10 in a process control computer 1 through the bus driver 3 to write the state of the process in an address in the storage device 12 which corresponds to the relay contact 8. When an operation instruction for lighting up a lamp 7 is outputted, the program 10 writes the state of the lamp 7 in an address of the storage device 12 which corresponds to the lamp 7 simultaneously with the output of said instruction.
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