PLC s ladder diagrams

J

Thread Starter

John Carter

Addresses are not needed but could someone assist me in designing a ladder diagram so then an input button is closed one output is to show
(the LED on output terminal to come on), then 62 seconds later another to come one.

When this button is pressed again they are to be turned off in reverse order with another 62 second delay between the first and second.

Electronic tuturals links welcome too!

Thanks for reading!
 
T

Theo Baarslag

I have to do this without a picture (it translates to plain text format), so I hope you can follow me on this. Examine when the input is high, and latch the first output (Latching is setting the output high, and having it remain high without the logic of the ladder rung having to remain true). Use the high condition of the first output to start a delay timer, of 62 seconds, and when the timer is done, latch the second output. When this second output is high, and the input is high again, unlatch the second output first. Also, use a timer-off to determine when this second output is no longer high, and delay this signal for 62 seconds again. Use the timer done of this signalto unlatch the first output.
In Allen-Bradley PLC5 ladder logic, the rungs would look like this:
rung 1: XIC <INPUT> OTL <OUTPUT1>
rung 2: XIC <OUTPUT1> TON <SWITCH_ON_DELAYTIMER (PRESET 62 seconds)>
rung 3: XIC <SWITCH_ON_DELAY_TIMER>/DN OTL <OUTPUT2>
rung 4: XIC <OUTPUT2> XIC <INPUT> OTU <OUTPUT2>
rung 5: XIC <OUTPUT2> TOF <SWITCH_OFF_DELAYTIMER (PRESET 62 seconds)>
rung 6: XIC <SWITCH_OFF_DELAYTIMER>/DN OTU <OUTPUT1>

This is not the most elegant solution, but I think it is the one that makes it the clearest.

Happy programming.

KR,

Theo Baarslag
PLC-/CIMspecialist for The IAMS Company, the leading manufacturer of dog- and catfood, Coevorden Plant,
The Netherlands
 
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