| 摘要 |
PURPOSE:To attain the serial transmission of data with a small number of signal lines by connecting a memory storing a user program to a CPU provided to each master and local programmable controllers PC, then connecting among these PCs with a cable or an optical fiber in a loop form. CONSTITUTION:A master PC1 is connected to one or plural local PC2 via a data highway 3 using a cable or an optical fiber in a loop form. Thus a PC network is obtained. Then addresses 1-N are allotted to those PC2 respectively, and the optical signal is converted into an electric signal through a photoelectric converting part 28 of PC1 and 2 each. This electric signal is supplied to a CPU32 via a serial input port 30. The CPU32 reads its own address to write the reception data to a memory 33 when the coincidence of address is obtained and to transmit the data to the highway 3 via a serial output port 31 and a converting part 38 when no coincidence is obtained with the address respectively. At the same time, a user program is stored in the memory 33 via a parallel input port 34. Thus the number of cables can be decreased. |
