Rockwell Automation Allen-Bradley Micro850, Оригинальное руководство пользователя

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86 Rockwell Automation Publication 2080-UM002L-EN-E - November 2021
Chapter 7 Motion Control
Simultaneous Execution of Two Movement Function Blocks (Busy Output = True)
The general rule is that when a movement function block is busy, then a
function block
with the same instance ( for example, MC_MoveRelative2)
cannot be executed again until the function block status is not busy.
Behavior of CommandAborted
Output
CommandAborted is set when a commanded motion is aborted by another motion command.
When CommandAborted occurs, other output signals such as InVelocity are reset.
Enable and Valid Status
The Enable input for read function blocks is level-sensitive. On every program scan with the Enable input as true, the function block will
perform a read and update its outputs. The Valid output parameter shows that a valid set of outputs is available.
The Valid output is true as long as valid output values are available and the Enable input is true. The relevant output values will be refreshed
as long as the input Enable is true.
If there is a function block error, and the relevant output values are not valid, then the valid output is set to false. When the error condition
no longer exists, the values will be updated and the Valid output will be set again.
Relative Move versus Absolute
Move
Relative move does not require the axis to be homed. It simply refers to a move in a specified direction and distance.
Absolute move requires that the axis be homed. It is a move to a known position within the coordinate system, regardless of distance and
direction. Position can be negative or positive value.
Buffered Mode For all motion control function blocks, BufferMode input parameter is ignored. Only aborted moves are supported for this release.
Error Handling
All blocks have two outputs which deal with errors that can occur during execution. These outputs are defined as follows:
• Error – Rising edge of “ Error ” informs that an error occurred during the execution of the function block, where the function block
cannot successfully complete.
• ErrorID – Error number.
• Types of errors :
• Function block logic (such as parameters out of range, state machine violation attempted)
•
H
ard limits or soft limits reached
• Drive failure (Drive Ready is false)
For more information about function block error, see Motion Function Block and Axis Status Error ID on page 99 .
General Rules for the Motion Function Block (Continued)
Parameter General Rules
MC_MoveRelative, MC_MoveAbsolute will be busy until final position is
reached. MC_MoveVelocity, MC_Halt, and MC_Stop will be busy until final
velocity is reached.