Scan time issue?

Good morning all. Quick background, I’ve had no real formal PLC training, pretty much self taught. I have 2 identical machines with a SLC 5/05, one machine I added a new ladder and integer file. The ladder has yet to be enabled in the ‘Main’ ladder. I noticed after I completed the programming that the ‘spinning ladder’ in the upper left corner spins a lot slower than the unmodified program(didn’t pay attention to spinning ladder before additions). I opened the S2 file on both machines and also noticed that the Free Running Clock appears much slower on the same machine. From the Scan Times tab all Scan Times appear to be the same. The Scan Toggle Bit is also much slower. Should I have concerns? Thanks for looking and appreciate any advice.

in most cases the speed of the spinning ladder icon is dependent on the COMMUNICATIONS speed between your computer and your PLC processor ... you'll usually see it spin a lot faster when using an Ethernet connection - when compared to an RS-232 serial port connection ...

if everything else is working OK - then I wouldn't worry about the spinning ladder ...

and welcome to the forum ...

That spinning ladder can be a good indication of how well windows and RSLinx is communicating with the PLC, but is not a good indicator of anything to do with what the PLC itself is doing.

The free running clock value should be advancing at the same rate in both PLCs, but if your laptop or RSLinx or some other network related issue is causing slower refresh rates when connected to one PLC versus the other, you are probably getting fewer updates per minute and getting the false impression that the clock is running slower. Look at the whole value of the free running clock in decimal form for a better idea of that (S:4).

EDIT: I misread your post, you are looking at the scan toggle bit. If the PLC is running a scan time of 50ms, you can bet that bit is toggling 20 times per second whether or not Windows can read and display it that fast.

Be aware that RSLogix will try to update everything you have visible or open while online. If you have three monitors and ten data table views open all at once, RSLogix will be asking the PLC for all that data repeatedly. This can impact the overall cycle rate at which the laptop screen is refreshed.

Also be aware that there's no such thing as two identical machines. There are always differences, sometimes subtle, other times not so much.

And welcome to the forum.

Thank you for the responses. Sorry I did not mention I’m looking at both machines remotely from the same computer via Ethernet connection. Something at the one machine must be slowing me down. Thanks again.