Rockwell Automation 1771-QB Linear Pos. - Manual (Page 62)

Chapter
6
6Ć1
Interpreting ModuleĆtoĆPLC Data (READS)
This chapter explains how to monitor module operation from a programmable
controller by reading and interpreting status block data that the module transfers
to the programmable controller’s data tables.
You must program the programmable controller to communicate with the Linear
Positioning Module through block read and block write instructions. The data
blocks are:
status block
parameter block
setpoint block
motion block
command block
The block read instruction transfers the status block data from the module to the
programmable controller data table. The block write instruction transfers the
parameter block, the setpoint block, the motion block and the command block
data from the programmable controller data table to the module. This chapter
tells you how to interpret the status block data. Chapter 7 tells you how to
format the parameter block, the setpoint block, and the command block data.
Chapter 9 explains the motion block.
The status block contains information on the status of each axis. Until the
module receives a parameter block, the status block consists of five words (i.e.
the default assumption of one axis). The size of subsequent status blocks
depends on the configuration you program through the parameter block.
Number of Axes Status Block Length
1 5 words - default
2 9 words - default
1 or 2 up to 33 words depending on
block transfer length requested
You can set the block transfer read instruction to include extended status
information by specifying a block transfer length of 33. If you specify a length
of 0 (or 64), the module returns the default: 5 words for one axis and 9 for two.
PLC Communication Overview
Status Block