174 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018
Preserving the Current Camming Direction
When Unchanged is selected or entered as the Direction, other position cam
parameters may be changed while preserving the current or previous camming
direction (same or opposite). This is useful when the current direction is not
known or not important. For first time execution of a cam with Unchanged
selected, the control defaults the direction to Same.
Reversing the Current Camming Direction
When Reverse is selected the current or previous direction of the position cam is
changed from Same to Opposite or from Opposite to Same. For first time
execution of a cam with Reverse selected, the control defaults the direction to
Opposite.
Specifying the Cam Profile
To execute a MAPC instruction, a calculated Cam Profile data array tag must be
specified. Cam Profile array tags may be created by the Logix Designer application
tag editor or the MAPC instruction using the built-in Cam Profile Editor, or by
executing an Motion Calculate Cam Profile (MCCP) instruction on an existing
Cam array.
The data within the Cam Profile array can be modified at compile time using the
Cam Profile Editor, or at run-time with the Motion Calculate Cam Profile
(MCCP) instruction. In the case of run-time changes, a Cam array must be
created in order to use the MCCP instruction. Refer to the MCCP instruction
specification for more detail on converting Cam arrays.
All but the status element of this Cam Profile array structure element are hidden
from the Logix Designer application tag editor. These elements are of no value to
the user. The Status member is used to indicate that the corresponding Cam
Profile array element has been calculated. If execution of a camming instruction is
attempted with any uncalculated elements in a cam profile, the instruction errors.
The type parameter determines the type of interpolation applied between this cam
array element and the next cam element, (for example, linear or cubic).
Cam Profile Array Checks
The Status member of the first element in the cam profile array is special and used
for data integrity checks. For this reason, the MAPC must always specify the cam
profile with the starting index set to 0.
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