status bit that shows a download was performed, ab slc5/04 and/or micrologix1200

[detrimental1]

Need to find a way to zero out some registers on 1st scan if programming was just downloaded. Want to differentiate between a 1st scan following a power off event as opposed to a 1st scan following a download / Does the processor record the fact that a download has been performed? Perhaps with a status bit? If I download the processor with my latest file, but someone has changed some setpoints after my last backup, via touch screen input, I want to zero out some registers that contain setpoints, so that I don't inadvertantly let the machine run with the wrong setpoints. In this case, the machine would not run until a machine tech came, and filled in the correct setpoints again. If just the power goes off, and then gets turned back on, I don't want to zero out the registers, as the setpoints will still be the ones that were in the machine when it was powered off.

 

[bernie_carlton]

Pick any data memory. Let's say N7:0.

In the OFFLINE FILE set N7:0 to zero.

On the first scan test if N7:0 = some number. Let's say 42.

If it is 42 then go on. Else perform whatever actions then set 42 into N7:0.

If you ever do a backup upload make sure to save it with zero in N7:0.

 

[detrimental1]

Response to 1st suggestion about setting zero in offline file

I appreciate the input. I think this is not the method I would prefer because this would require that I would have to modify the programming each time after I did a save from the machine. After the save, the n register you suggest will again have a non-zero value in the register, and I would have to go set it back to zero. I am hoping for an "automatic" solution, rather than doing a manual change. What if I forget?
Hoping for a bit that gets sets at download, or some way to automatically know that the processor went thru a certain sequence of progrm/run patterns that identifies the download event, somehting different than a simple power up. Set a bit during or at the end of the download, see it set on start-up, cause the data files to zero, then program in an automatic reset of the bit. Now I can do a back-up normally, and the bit is in the right state always, 0 if the program did not just get downloaded, 1 if it did. Maybe no such "download" marker exists, and I have to take a "remember every time" manual change approach.