| 摘要 |
PURPOSE:To monitor circulating data simply with good transmission efficiency, by concentratingly monitoring the data at the monitor station and performing the abolition of the circulating data completely, through the provision of two types of 2-bit flag area in the data format. CONSTITUTION:A monitor station SV monitoring data and a plurality of node stations ND1-ND4 are connected in loop with a transmission line to constitute the loop network. In the data format of the time slot used for this network, a control area 1, opposing party address area 2, data area 3 and check bit area 4 are provided, and the area 1 is provided with a monitor station passing flag bit SV flag and a usage display flag bit B/I flag. When data are transmitted at stations ND1- ND4, the B/I flag is set, and the SV flag is set when the time slot passes through the monitor station SV, and when both the SV and B/I flag are detected at the monitor station SV, the data of the time slot is abolished. |
