Implement Latching and Unlatching of output with a particular time delay in PLC using Ladder Diagram
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Implement Latching and Unlatching of output with a particular time delay in PLC using Ladder Diagram
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Plc Scada
Implement Latching and Unlatching of output with a particular time delay in PLC using Ladder Diagram
Latching is done the same way as in previous program. The only difference in this program is that Timer On is added to unlatch the output after 10secs. And to operate unlatching of output, instead of using stop PB, Timer On done bit passed to Stop XIO contact which operates automatically.
Time Delay to turn output off can be decided by operator in terms of Multiplication of Time Base and Preset. It means if time base is 0.1 and we want to generate 10secs of time delay then Preset value must be set to 100 so that “100 * 0.1 = 10secs”.
When input I:1/0 is pressed momentarily, output goes true and it is latched.
When output is latched, Timer T4:0 is enabled and EN bit goes high.
As long as O:2/0 is true, Timer T4:0 is active and accumulator value is incremented.
When Timer count (Accumulator value) is equal to Preset value, Timer Done Bit T4:0/DN goes high which works as a Stop PB of previous problem causing output to go false.
Important thing to note here is that when timer is ON and you press Start PB as soon as Time delay is over, output is latched again. So during those 10secs, Start PB has no effect on output at all.
