text: <s>[INST] MDAC or Other? Summary: Flying Knife Control I am working on a flying rotary knife control where we are removing a mechanical clutch and replacing it wil a servo drive. I am relatively green to using the more complex servo motions outside of MAM, MAS, MAJ ect. I've been reading through all of the different functions in the Motion Instructions manual and other manuals and the MDAC seems like what I need. Here's a breif summary of the application. A web of film is feed through a set of rollers and is actuated to run and feed out a specific length of film. As the film is being fed a cut position is calculated to actuate the knife servo. The knife servo needs to ramp up to match the surface speed of the film and make 1 revolution cutting the film and returning to the start positon. I currently have the master servo units setup as inches and the knife as revolutions. I have the unit working now using two MAM's and calculating the speed of the knife based on a snapshot of the feed speed when the knife is signaled to cut. It is working like this but is not optimal as the feed is decelerating and the knife is at a constant speed so there is a mismatch at the end of the cut because of this. Depending on cut length and feed speed the deceleration could occur at different points so I feel the two axis speeds need to be tied together somehow. I played around with the MDAC some but was unable to get it to work. The knife MAM would fault on a 95 which from what I could find is a error with the speed units not being set to Units per master which they are. I'm not having much luck getting this to work so I'm looking for some direction or insight as to the best way to accomplish this task. I am by no means stuck on using the MDAC and am open to any ideas or suggestions. [/INST] I think I've figured it out. After 2 hours of reading I found the necessary information on setting up the MDAC. What I had missed was setting up the Lock Position / Lock Direction in the MAM correctly. I set the Lock Direction as Position forward only and the Lock Position as the Calculated cut position based on the master position. The Speed units are all set to units per master unit and I calculated out the MAM speed based on Slave Rev / Master Inch. The MDAC also needs to be cycled off and on for every MAM cycle. Now I just need to work on tuning the spikes out. For Reference the majority of the usefull information I found was in Chapter 6 - MDSC Functionality of the Motion Instructions Reference Manual. \\n </s>