Posted 15 Sep 2015 Hello everyone, I am new to omron stuff. I have been given a task to execute a timer with retentive values on power off. I want to retain timer value when plc turn on after shut down. Timer should be start from where it stops on power failure. How to do that could anyone help me out here? Share this post Link to post Share on other sites
Posted 15 Sep 2015 Instead of a timer, you could decrease a DM with a 0.1 sec. pulses, and compare that DM with 0. Share this post Link to post Share on other sites
Posted 15 Sep 2015 And how to store DM locatiosn? I have CJ1M CPU13. Does this CPU contain DM locations? Share this post Link to post Share on other sites
Posted 16 Sep 2015 All CPUs contain data memory (DM). Timers are not retentive through power cycle. You could consider making your own as pfort suggested. Some DM areas are retentive, and so the current value would remain after a power cycle. Instead of a timer, write a decrement on a data register and trigger it from a built-in clock pulse signal. Do a compare to see when it reaches zero so you know when the 'timer' is done. 1 person likes this Share this post Link to post Share on other sites
Posted 16 Sep 2015 Yes, I have made a data register with decrement on built-in 1s pulse. But I have made a FB block and write a code in it and check the 'retain' box. Would it retian data on power off or Do I have to save my data in DM locations? and how would I save data in DM location? Could you give me an example? Share this post Link to post Share on other sites
Posted 16 Sep 2015 Using the retain box inside a function block will make that address retained through a power off condition. I believe FBs by default use the HR area for retained memory, but that is fine, it will work just like DM. Make sure to one shot the decrement instruction. It sounds like you are on the right track, keep going. 1 person likes this Share this post Link to post Share on other sites
Posted 16 Sep 2015 Yes, I've put positive edge detection on 1s pulse bit so it decreases only once on positive pulse.. Share this post Link to post Share on other sites
Posted 16 Sep 2015 You could simply continuously copy the timer value to a data register, and move it to the timer in the first scan. Share this post Link to post Share on other sites
Posted 23 Oct 2017 On 9/16/2015 at 0:05 AM, areeeb1 said: Yes, I have made a data register with decrement on built-in 1s pulse. But I have made a FB block and write a code in it and check the 'retain' box. Would it retian data on power off or Do I have to save my data in DM locations? and how would I save data in DM location? Could you give me an example? Hello All, I am new in PLC also. I am facing the same trouble here. could you help me about how to make data register with decrement on built-in 1s pulse? I have no idea how to make this. Thanks for your advice. Share this post Link to post Share on other sites
Posted 23 Oct 2017 It's in the PLC instruction manual. Increment ++/++L Decrement --/--L Remember to use a rising edge LD instuction ahead of the Decrement instruction. Share this post Link to post Share on other sites