Preferential control method and device null of ru - punetsutowa -

摘要

PURPOSE:To use efficiently a transmission line without unnecessary polling by stopping the equalizing control for each master priority level in a node station until the master priority level becomes equal to the lowest master priority level of polling of the preceding cycle in each cycle and starting the equalizing control for each master priority level after the master priority level becomes said lowest master priority level. CONSTITUTION:A counter 17 indicates the master priority level, and a counter 18 has the one-bit length and indicates a slave priority level. When an increment signal is supplied to the counter 17, the master priority level is switched to the lower level by passage of one polling signal. The equalizing control is stopped by this control. When a polling signal POL passes, the counter 17 is counted up to indicate master priority level '1'. In this case, contents of the counter 18 are not changed, and slave priority level '1' is held as it is. As the result, polling of master priority level '1' and slave priority level '0' are not performed, and the equalizing control is stopped.