Kinetix 300 "Active Index"

Just wondering if anyone has run into this.

I have a ML1400 talking to a Kinetix 300. I have a couple indexes I would like to switch between in order to accomplish my moves. My plan is to write a number for the index I want to run to the Starting Index address in the output assembly, and then Start Motion.

I would like to confirm that the starting index actually switched before I start motion. I know that there is an Active Index DINT in the Input Assembly.

My question is, when does this change? Does it change when I change the starting index or does it change after I start motion?

Reading the manual it SEEMS it doesn't change until motion is started, but it doesn't state this specifically. I hoping it's not, because looking at the Active Index to confirm will make this easy!

If that is the case, is there any way any of you have found is a good way to confirm the starting index has switched in the servo?

Well Techconnect answered me first.

The Active index only changes after motion starts, and there is no way to read in what the next index in the queue is going to be. So I guess I'm just going to use a timer to make sure the servo doesn't start before the starting index is written. I'm worried about the timing for my explicit messages.

Could you not do a read message after the write was complete in order to confirm the correct value was written?

I ran into the same problem in a Kinetix 300 + MicroLogix 1400 application.

My assumption was that the Active Index was the one that was queued up and ready to go, but I guess it's just as valid to say that the Active index is the one that's actually been started.

In my case I programmed in a 250 ms delay after the MSG /DN bit is true on the MSG that sets the Index number.

So far it's been entirely reliable so I never went back to fine tune or test the function further.

I am encountering a similar problem with my Micrologix1400 and Kinetix300 set up. One of the jog buttons is pushed, then the PLC index number is changed, then the message is sent, 150 ms later the drive "Enable" input is made, 850 ms later the "Start Index" input is made. I am finding that the first motion follows the previous index, while subsequent jogging attempts, no matter the direction, behave correctly. I am currently wondering whether the message statement timing is messing things up or if it something particular about Kinetix index operation that requires a pattern interrupt.

Regards,

Adam