1) When plc is in RUN mode, K20 is sent to the preset value register SV100. If the reset behavior is OFF at this time, K20 in SV100 is sent to the elapsed value register EV100.
2) Each time a rising edge of the counter logic line X0 is detected (the state changes from OFF to ON), the value in EV100 is decremented by one.
3) When the value in EV100 is reduced to “0â€, the contact of counter C100 acts and remains, that is, the normally open contact closes and the normally closed contact opens.
4) Each contact of C100 is reset when the rising edge of reset logic line X1 is detected (ie, OFF→ON). When the falling edge of the reset line X1 is detected again (ON→OFF state change), the value K20 in the SV100 is again transmitted to the EV 100 to be ready for counting.
5) During the counting process, if the reset line changes from OFF to ON, the EV100 is reset to "0", but the contact of C100 does not operate. The value K20 in the SV100 is again sent to the EV 100 until the reset line is turned from ON to OFF.