Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 162)

Chapter
8
8Ć1
Programming
The previous chapter told you what information to put into and monitor
from the data blocks. This chapter tells you how to generate a ladder
diagram program to transfer these blocks between the data table and the
servo positioning assembly.
The main objectives of a program for the servo positioning assembly are
to:
transfer the status block from the 1771-M3 controller to the data table
transfer the parameter, moveset, and command blocks from the data
table to the 1771-M3 controller
You can use a block transfer read instruction to continually transfer the
status block from the 1771-M3 controller to the data table.
You can use a single block transfer write instruction to transfer either a
parameter, moveset, or command block, from the data table to the
1771-M3 controller. Your program must manipulate the address of the
block to be transferred by the block transfer write instruction so that the
right block gets there at the right time.
After power-up, the first block to send is the parameter block. In the
parameter block, you must include address pointers for (Figure 8.1):
parameter block
command block
first moveset block for each axis
Once it receives this information, the 1771-M3 controller can start to
request the block it needs by sending its address pointer in the status
block. After receiving the parameter block, the 1771-M3 controller
requests the first moveset block for each axis.
In each moveset block, you must include the address pointer for the next
moveset block if one exists for the axis.
Chapter Objectives
Programming Objectives