How to program a Less Time On logic on Logix5000?

[wendaiyu 0]

Hi, guys, could you tell us how to program a Less Time On logic on Logix5000? E.g. if the duration of input “tagI” on is Less than 3s, the output “tagO” will be on. Thanks a lot.

[PLCMentor.com 60]

If I understand what you are asking, you could just use tagI to run a timer (TON) set for 3 seconds and activate your output - tagO - with the timing bit (.tt). That would activate the output for the first three seconds each time tagI comes on.

[wendaiyu 0]

Thanks for your time. But I mean: if the total execution time of "tagI" is less than 3s, then "tagO" will be ON; if the total execution time of "tagI" is >= than 3s, then "tagO" will keep OFF.

[ASForrest 12]

This will do it: BST XIO Tag_1 ONS OneShot XIC Tmr_Tag1_On.TT OTL Tag_0 NXB XIC Tag_1 TON Tmr_Tag1_On 3000 0 BND The second part of the rung runs a timer while Tag 0 is on. The .TT bit is active only while the timer is timing. Once the timer is done (i.e. Tag_0 has been on for 3 seconds), it turns off. So the first part of the rung watches for Tag_0 to turn off while the timer is still timing. If it does, Tag_1 is latched. If Tag_0 has been on for over 3 seconds, the .TT bit will be off, so when it turns off, Tag_1 won't be latched. Obviously you'll need to have some way of unlatching Tag_1 at the relevant time. If you want you can make it two separate rungs; the only thing is to make sure that the XIO Tag_1 ONS OneShot XIC Tmr_Tag1_On.TT OTL Tag_0 rung is placed before the rung with the timer, or it will not work.

[panic mode 246]

just add 3sec timer to your condition result you ask for is NC contact with timer done bit

[PLCMentor.com 60]

Yeah I think panic pretty much summed it up. If you take my first answer and instead of using the .tt bit to turn on TagO use the .dn bit with an XIO (or Normally Closed) to turn on TagO. Of course this assumes from your post that any time less than 3 seconds of on time for TagI will result in TagO being on. So if TagI is off then TagO should be on (0s being less than 3). If we are all still missing this then maybe you could post more on the application and we may understand better what you are trying to do.