host control of a path in position and time

I have an application where I want to follow a path in (position, velocity, time). A host computer will provide a new position and velocity every 10ms, indicating where the axis must be on, e.g., the next but one 10ms tick. I want PMAC to execute PVT commands to follow the commanded positions. The timing accuracy of commands must be ~10us. In the past I have handled a similar application using PMAC's DPRAM to pass positions from the host to the motion program, with some flags in the DPRAM to control the data flow. Is there a way to pass positions to a motion program in power PMAC with this type of timing synchronization?

I think the only real change here is that you will be passing information through Power PMAC's "user shared memory buffer" rather than DPRAM. The "USHM" is in Power PMAC's main memory, which only has one physical hardware port, but in software, you can use it in the same manner as you used DPRAM in Turbo PMAC. You host computer will dump the move information into registers in USHM, and the Power PMAC will "handshake" this in other registers in USHM. Logically, it looks to me like the operation will be the same.

Thanks. Which of the manuals will tell me more about USHM?

There's not much to it. The best place to start is the training slides chapter on shared memory (which you can access from this forum), then (if necessary) to the software reference manual for specific commands to set up access. You are just using pointers or arrays to get at specific registers in the buffer.