RUN HOURS for PUMPS applicatoin

[samuel_12]

Dear Friends , I have an application three pumps running with respect to maximum run hours . I want to create a ladder in any of the PLC for the application as follows : example : Pump1 run for 3 hours Pump2 run for 6 hours Pump 3 run for 1 hour , IN this case i want my pump 3 to run first bcoz it has less number of run hours so kindly please help me to create a Ladder LOGIC i try using less than equal to but is not success please help me out , present PLC iam using Mitsubishi FX3u PLC .

[kaare_t]

Have you done anything so far? What kind of software/"ladder" are you using (GX, GX IEC, GW2 - Simple Ladder, Structured Ladder...)??

[Crossbow]

In the Q or L there are commands that can be used to create a data table or search a series of of registers for the min or max values. So search the 3 values for the low one, the MIN command will return a position in the table. That says which one has lowest hours. Those commands don't exist in the FX3U. So you need to write a couple compares. Think about the logic this way: If 1 is less than 2, check if 1 is less than 3. If this is true, 1 has the least hours. If it is false, then 3 is the lowest. You will have to write several sets of this logic to see all possible combinations. Or just get a stronger PLC with the min and max search commands.