Ultra3000i Dnet moving to preset position problems

I have alomst completed a integration of a Dnet Ultra3000i servo controller but I'm having a few issues. I've attached the ultraware program from the servo controller to this thread. I am using assembly object 5 and 12 for Dnet communications. I am able to home the servo, move the servo in velocity mode as well as move the servo in indexing mode all through Dnet. Howerver, When I change the operation mode to Preset position mode, set position 0 to say...1000 counts and set start index high, nothing happens. When I disable the drive and then enable the drive it moves into the commanded position. If I home the servo while in preset position mode, it will home ok but right after it zeros, it will move to preset 0. I have tried to control the servo in preset position mode via Dnet as well as via direct I/O and they both do the same thing. I dont have "start index" assigned to any inputs I have all bits in my masked word set to 1, I'm not sure what else it could be.
Once I get the preset position mode to work correctly my plan is to store about 8 positions in the PLC. When needed, I'll send the positions to Preset 0 via the assembly object and then trigger preset 0 position.
I hope someone can help me out. I'm starting to pull my hair out!!!

any ideas?

Is there a reason why you want to use the Preset mode? Why not just use Indexing mode and have your PLC change the position value of index 0 via DeviceNet?

I was going to say the same thing. I have only used Indexing mode with DeviceNet or physical IO. It gives you a lot more flexibility. A few thing I noticed is that under DeviceNet, the Enable behaviour is set to 'both' but there is no physical enable input. Usually, input 1 is the enable input.

kolyur said:

Is there a reason why you want to use the Preset mode? Why not just use Indexing mode and have your PLC change the position value of index 0 via DeviceNet?

Click to expand...

This servo is on a pick and place. There will be about 8 positions that may run in no particular order. If I use the indexing mode then I need to take the current position subtract it from the position I want to go to, figure out the difference and then send that calculated value to the servo. I can do it that way but I figured there was more code/work to using the indexing mode. I figured the Preset Position Mode would be cleaner.
Am I correct?

johnfarrugia said:

If I use the indexing mode then I need to take the current position subtract it from the position I want to go to, figure out the difference and then send that calculated value to the servo.

Click to expand...

That's true if your motion profiles are Incremental. But if you use Absolute positioning then all the positions are referenced from the zero point. The only disadvantage is that the servo must be homed before you can do any positioning.

That should work! I'll try it out.

In the indexing panel, under mode, how is jog used? I want to allow the operator to jog the pick and place manually so I was going to place the servo into velocity mode and allow the operator to enable forward or reverse. Is this a good way to do it?

I would recommend using Indexing mode to jog your pick and place. If a motion index is set to Jog, the index will only run as long as the Start Index input is held high. Plus, it will stop if the Maximum Distance is reached. To make it jog in the opposite direction, the Maximum Distance value has to be negative. So if you want to jog both ways you have to use either two motion profiles or change the Max Dist parameter on the fly.

When I used jogging on my last project, I didn't have Devicenet so I set up two motion profiles for forward and reverse jog. The operator had a 3-position center-off momentary switch. Pushing and holding the switch either direction would set the proper motion select bits, then after a short delay set the Start Index output. It works pretty good.