Cycle Count retention during power loss

This is my first post but I have a couple questions. First, the PLC that I'm using is a SLC 5/05 with RSLogix 500 V.9.00. What is the best and most efficient way to count cycles when dealing with cycle counts in the 500K range? I just want to know if there is an easier and more "cleaner" way to do it than what I'm doing. Also, during a power loss (we get frequent facility power losses), can I retain that cycle count in the PLC, so that we can start up again and begin cycle counting where we left off before the power loss?

All and any help or advice is much appreciated.

- Don

Welcome to the forum.

Use a floating point number address, a one shot, and an add instruction.

  Cycle_Start   B3:??

-----] [--------[OSR]-----------+-ADD----------+

                                |Source A: F8:0|

                                |Source B:  1.0|

                                |Dest      F8:0|

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

A floating point number will be good for counting to 16,777,216 cycles, then it starts to loose resolution in the 1's column.

All addresses in a SLC5/05 are retentive, they do not change unless operated on by an instruction, so unless some other instruction changes the count value then it will be retentive though a power bump.

The value is not retentive through a PLC program download. If you download the program then the last saved count will be downloaded as well. You will need to establish some kind of protocol for making sure the offline value is updated to the correct value prior to a download. One way is to keep the key switch in the run position and placing a tag on the key reminding you to upload the correct cycle count first.

For critical cycle counts I either use an external counter or if an HMI is attached I log the cycle count to a database.

Thank you. Looks pretty simple.