Need help in a small plc program

[rohit_plc]

Hello all, I need help in a small plc program in Allen Bradley plc.

Need to generate a 1 second pulse on every ON and OFF of a bit.

Suppose for example a bit b3:0/0 when ON an output (o:0/0)will be on for 1sec. And then OFF and same bit (b3:0/0)when OFF same output (o:0/0) will ON for 1sec. And then OFF.

 

[janner_10]

Use the YourTimer.TT bit to do this.

 

[nhatsen]

Need to generate a 1 second pulse on every ON and OFF of a bit.

That's a request that appears from time to time. Here's a solution:

http://www.plctalk.net/qanda/showpost.php?p=708952&postcount=13

 

[geniusintraining]

Looks like the OP is using RSLogix 500 (not 5000)

Use a S:4/x bit, this is a preset bit that will reset every x just change x to a number that works for you, I think 5

Or you can roll your own and use the ACC from a timer running at your given time

Not sure what page but.... http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1747-rm001_-en-p.pdf

 

[daba]

Use a TON for the ON pulse, trigger with XIC (from your example) B3/0 : if B3/0 is not on for at least 1 second, then seal it in with the TON.TT bit. That same bit is your 1 second pulse for when B3/0 comes on.

Use another TON for the OFF pulse, trigger with XIO B3/0 : again seal it in with the TON.TT bit if B3/0 can be OFF for less than 1 second. That same bit is your 1 second pulse for when B3/0 goes off.

Of course B3/0 can't toggle faster than once per second, or the pulses will get missed, I assume that's not an issue.