Latching Bit?

[Deke2006 0]

Hi, Is there a latching bit, that when set it stays set even if loss of power? Thanks, Deke

[gtsuport 61]

HR bits will retain status through a power failure. You should use the KEEP (11) instruction with the HR bit. Hope this will help.

[Deke2006 0]

Thanks!

[Sergei Troizky 26]

Not at all. HR maintains its status regardless of the way it was set.

[scottmurphy 1]

What gtsupport probably meant, was to use an instruction that will not be reset when power is re-applied, by using a conditional output. If a set/reset, or keep is used, and the reset conditions are not enabled when power is applied after a power failure, then the status of the bit should be retained.

[gtsuport 61]

I will agree with your statement. My concern is if the initial logic after power is restored does not maintain the "on" status, the bit will reset. ____ scott posted while I was replying. That is exactly my point, but much better wording. Edited 4 Sep 2007 by gtsuport

[Sleepy Wombat 27]

The following logic will also work without the use of the SET RESET / KEEP The HR bits if true before power down will be true for the first scan of the program at power up.. hence a set / keep function will maintain their state but so to will the self latch logic...