MC_ReadCamTableMasterPosition
The function blockMC_ReadCamTableMasterPosition can be used to calculate the master position for a given slave position. While the slave position for a given master position must be unique, the inverse is not true. In order to limit the number of master output options for the function block, for a given master position (MasterStartPosition) the smaller (MasterLow) and larger master position (MasterHigh) for the slave value is output.
For example, for the cam plate in Fig. 1, for a slave value of 80 and a master start value of 180, the output values are 225 for MasterHigh and 135 for MasterLow. If the cam plate is cyclic, for a master start value of 90 in addition to the MasterHigh of 135 a MasterLow of -135 is calculated. In the linear cam plate case (non-cyclic) only the value MasterHigh is shown as valid in Fig. 2.
Fig. 1
In cyclic cam plates with hub the master position can not only lie in one of the cycles adjacent to the StartMasterpos, but several cycles further, depending on the slave position.
Fig. 2
The master position is calculated with numeric algorithms, the precision of which can be set via the variable MasterAccuracy.
Inputs
VAR_INPUT
Execute : BOOL;
CamTableID : MC_CAM_ID;
SlavePosition : LREAL; (* absolute slave axis position *)
MasterOffset : LREAL; (* E *)
SlaveOffset : LREAL; (* E *)
MasterScaling : LREAL := 1.0; (* E *)
SlaveScaling : LREAL := 1.0; (* E *)
MasterStartPosition: LREAL; (* Master position to start the iteration from *)
MasterAccuracy : LREAL; (* Master iteration accuracy *)
END_VAR |
Execute |
The command is executed with a rising edge at input Execute. |
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CamTableID |
ID of the cam plate for which the calculation is carried out |
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SlavePosition |
The slave position for which the master position is sought |
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MasterOffset |
Offset to the master position of the cam plate |
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SlaveOffset |
Offset to the slave position of the cam plate |
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MasterScaling |
Scaling of the master position of the cam plate |
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SlaveScaling |
Scaling of the slave position of the cam plate |
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MasterStartPosition |
Start position of the master |
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MasterAccuracy |
Precision for the calculation |
Outputs
VAR_OUTPUT
Done: BOOL;
Busy: BOOL;
Active: BOOL;
Error: BOOL;
ErrorID: UDINT;
MasterLow: ST_CamMasterData; (* position information of the lower bound master position *)
MasterHigh: ST_CamMasterData; (* position information of the upper bound master position *)
END_VAR Done | Becomes TRUE, if the coupling was successful and the cam plate is active. |
Busy | The Busy output becomes TRUE when the command is started with Execute and remains TRUE as long as the command is processed. When Busy becomes FALSE again, the function block is ready for a new command. At the same time one of the outputs, Done or Error, is set. |
Error | Becomes TRUE, as soon as an error occurs. |
ErrorID | If the error output is set, this parameter supplies the error number. |
MasterLow | Master position is smaller than the MasterStartPosition in the data structure ST_CamMasterData |
MasterHigh | Master position is smaller than the MasterStartPosition in the data structure ST_CamMasterData |