Posted 4 Sep 2007 Hi, Is there a latching bit, that when set it stays set even if loss of power? Thanks, Deke Share this post Link to post Share on other sites
Posted 4 Sep 2007 HR bits will retain status through a power failure. You should use the KEEP (11) instruction with the HR bit. Hope this will help. Share this post Link to post Share on other sites
Posted 4 Sep 2007 Not at all. HR maintains its status regardless of the way it was set. Share this post Link to post Share on other sites
Posted 4 Sep 2007 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. Share this post Link to post Share on other sites
Posted 4 Sep 2007 (edited) 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 Share this post Link to post Share on other sites
Posted 4 Sep 2007 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... Share this post Link to post Share on other sites