Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 85)

Formatting and Interpreting Data Blocks
Chapter 7
7Ć3
The first block transfer after power-up writes a 6-word status block into
the data table. After that, the status block consists of 6 words for a 1-axis
system, 10 words for a 2-axis system, or 14 words for a 3-axis system.
You establish the address for the status block through the block transfer
read instruction. Because axis command and status data is stored in the
data table, axis motion control can interact with other axes, discrete I/O,
and report generation.
Parameter Block
The parameter block for a 1-axis system has 25 words; a 2-axis system
has 44 words; a 3-axis system has 63 words.
You specify parameters for each axis separately. You specify parameters
such as:
software travel limits
home position
servo gain
global accel/decel rate
rapid traverse rate
In the parameter block, you also specify the address of the parameter
block, the command block, and the first moveset block for each axis.
With these addresses, the 1771-M3 controller can ask (through the status
block) for the block it needs at any particular time.
The processor transfers the parameter block to the 1771-M3 controller
through a block transfer write. This provides axis parameter information
after a power-up and after a command block commands a reset or new
parameters.
Moveset Block
A moveset block describes a sequence of axis moves. You can program
axis motion to provide either single-step moves or continuous moves.
Each move requires a minimum of three words (a single-move control
word and two words to define position or dwell time) and can include
three optional words (a rate word, an accel word, and a decel word) for a
total of six. A moveset control word applies to the entire block. If
additional moveset blocks are needed, you also need a next-moveset-point
word. A moveset block can be 64 words long maximum and describe 21
moves maximum. To describe 21 moves in a single moveset block, all 21