5. Loop Instruction Design Examples 5.2 Reservoir Level Control Y10 Y11 X0 Y1 Y0 X1 Control Purpose: z Enabling the abnormal situation alarm and draining water from the reservoir when the level is above the upper bound. z Enabling the abnormal situation alarm and pouring water into the reservoir when the level is below the lower bound. z Enabling the mechanical failure alarm if the upper bound sensor X0 is still ON after draining water for 10 minutes. z Enabling the mechanical failure alarm if the lower bound sensor X1 is still ON after pouring water for 5 minutes. z Resetting all the alarms and valves when the level is in normal position. Devices: Control Program:
DVP-PLC Application Examples 5-3 Device Function X0 X0 turns ON when the level reaches the upper bound. X1 X1 turns ON when the level reaches the lower bound. Y0 Draining valve Y1 Pouring valve Y10 Abnormal situation alarm Y11 Mechanical failure alarm X0 X1 CALL P0 X1 X0 CALL P10 X1 X0 ZRST Y0 Y1 ZRST Y10 Y11 ZRST T0 T1 FEND FEND CALL P0 CALL P10 ZRST Y0 Y1 ZRST Y10 Y11 ZRST T0 T1