Block transfer sequencing, 10ć2, Sample application programs chapter 10 – Rockwell Automation 1771-QB Linear Pos. User Manual

Page 146

Sample Application Programs

Chapter 10

10Ć2

Figure 10.1

Overview of Block Transfers

PLC

Data Table

Status

Block

Parameter

Block

50100

Block Transfer Read

Setpoint

Block(s)

Motion

Block(s)

1771-QB

Module

Status

Block

Parameter

Block

Setpoint

Block(s)

Motion

Block(s)

Block Transfer Write

Command

Block

Command

Block

To ensure correct block transfer sequence on powerup, it is recommended that
the programs:

make parameter block transfer conditional on the status block’s ready bit

being low

make setpoint block transfer conditional on the status block’s setpoints

received bit for this control loop being low and on the ready bit being high (if
you’re using setpoint blocks)

make the next motion block transfer conditional on the block transfer toggle

bit changing from the state it was in prior to the transfer of the previous block

make command block transfer conditional on the setpoints received bit and

the ready bit both being high

if you aren’t using setpoint blocks, make command block transfer conditional

on just the ready bit being high

Block Transfer Sequencing