| 摘要 |
PURPOSE:To detect a slave station requesting polling data in a short time at the control station side, by providing weighted resistors and switching means every slave station and obtaining the synthesized value of currents flowing to each resistor with a given voltage applied. CONSTITUTION:A detection circuit 12 is provided to a control station 11. Slave stations 1-1,...,1-n,...2-1,...,2-n... are provided with the series circuit of resistors R1-1,...,R1-n,...,R2-1,...,R2-n and relay contacts S1-1,...,S1-n,..., S2-1,...,S2-n,.... Each resistor is weighted by 1/2<0>r...1/2<n-1>r depending on the slave station group. When a control station 11 inquires the presence of polling data, since the relay in the slave station having transmission data is ON, the current (i) flowing to the terminal E of the detection circuit 12 is changed with the weighting of corresponding resistor, and this is in A/D conversion to identify the corresponding station having transmission data. |
