Rockwell Automation Publication 2198-UM004A-EN-P - October 2019 301
Motion Control in PR Mode Chapter 11
at the moment when PR executor is read, thus they will not enter the
generator. The arithmetic operations commands will be executed when
entering the PR executor; however, the execution time varies with the
computing duration and the next command cannot interrupt. The PR
executor can consecutively complete at least 20 PR commands with
interrupt commands (INS) and without delay time setting within 1 ms. If
there is a PR command that hasn't been completed within 1 ms and a new
PR group has been sent to the executor by the queue, the new PR group
will then replace the previous one. In other words, instead of executing the
PR group that hasn't been completed, the executor will start executing the
new ones. However, if a new PR group hasn't been sent to the executor yet,
the executor will continue to execute the unfinished PR command.
• Motion Command Generator: Motion commands include speed
command and position command. The PR executor will send this type of
command to the motion command generator. This generator has a buffer
for temporarily storing the next motion command and all motion
commands are integrated here.
Motion commands can be executed as soon as they enter the generator. If
other motion command (with interrupt setting) also enters the generator,
it will be integrated with the current command in the generator and the
integration is based on the setting. The setting includes whether multiple
motion commands are sequence commands and whether it is set with
overlap or interrupt function; all integration varies with each PR
command setting.
Sequence Command Execution
Configurable commands in PR command are motion commands, which are
position and speed commands. A sequence command is a motion command
without an overlap or interrupt function. The following command will start to be
executed only after the delay set in the previous command is over. For position
commands, the delay time starts to count after the target position is reached. For
speed commands, the delay time counting starts after the target speed is reached.
Consecutive Position Commands
When the PR executor receives two position commands consecutively, as they are
not set with interrupt or overlap functions, the PR executor will issue the first
position command to the motion command generator and the generator will
start the first part of position control. After the first position command
completes, if no delay time is set, the PR executor will issue the second position
command for the generator to start the second part of position control.
If the first position command is set with a delay, the PR executor starts counting
the delay time right after the motor reaches the target position. Then, it issues the
second position command to the generator for the second part of position
control as shown in Figure 131
.
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