Free Running clock

[FONT=&quot]In Logix 500 there is a free running clock at S:4 of the system status word. By, for example, picking S:4/14, I get a suitably pleasant on off of a single bit. Suitable for blinking an OTE output. Can i do something similar to that in Logix 5000? The manual is too..oo long. Even my PDF search routine doesn’t know where to look.[/FONT]

Found it!
You can create a tag of type Timer and name it Free_Running_Clock. Create a timer that will reset when it reaches 2^31 counts. Then you can use the bits from the timer ACC just as you use the free running clock bits.

However, the CLX platform supports timed periodic tasks. You can use these to create flasher bits without using timers.

For some reason, searching this site for Free Running Clock didn't turn this answer up.

Congratulations - you have found a couple of the many ways to generate a fixed on-off cycle bit.

Flashing lamps is an easy task, and doesn't demand timing accuracy, as the human eye cannot see the inherent variations that can exist due to scan time considerations.

Using periodic tasks can alleviate those variations, and is a must for when you have to have outputs that are "accurate". But you've still got to get those outputs to the real world in a timely fashion, and not rely on the normal RPI settings for the outputs.... cue the IOT instruction.

Don't reset the free running timer. Unconditionally unlatch accumulator bit 30. You will never time out and you won't have an odd interval while the timer resets.

      FreeRunningTmr.acc.30

--------------(U)-----------------+-TON---------------+

                                  |FreeRunningTmr     |    

                                  |ACC               0|

                                  |PRE      2147483647|

                                  +-------------------+