MCFB_StepLimitSwitchFastInput
Description
This function block performs a homing function by searching for an external physical switch. The switch must be connected to one of the two fast inputsThe inputs are taken into account at each cycle depending on the system periodicity (for example each millisecond). Under certain circumstances this can be insufficient when more accuracy is needed, or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g. when a sensor sends a rising edge), the detection of a signal occurs faster (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action on the Axis' AKD drive. The Axis will move and when a fast inputThe inputs are taken into account at each cycle depending on the system periodicity (for example each millisecond). Under certain circumstances this can be insufficient when more accuracy is needed, or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g. when a sensor sends a rising edge), the detection of a signal occurs faster (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action is triggered, the triggered axis will then perform an absolute move to the latched position.
The following figure shows the function block I/O:
Figure 7-252: MCFB StepLimitSwitchFastInput
Input
Execute |
Description |
Request the homing step procedure at rising edgeA rising edge is the transition of a digital signal from low to high. It is also called positive edge. Outputs are reset when execute input is false. |
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Data type |
BOOL |
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Range |
[0 , 1] |
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Unit |
N/A |
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Default |
— |
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AxisID |
Description |
Structure for specified Axis desired to home |
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Data type |
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Range |
[1 , 256] |
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Unit |
N/A |
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Default |
— |
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Direction |
Description |
Define the axis homing direction
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Data type |
BOOL |
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Range |
[0 , 1] |
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Unit |
N/A |
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Default |
— |
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LimitSwitchMode |
Description |
Limit switch state to complete homing
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Data type |
DINT |
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Range |
[0 , 1] |
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Unit |
N/A |
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Default |
— |
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Velocity |
Description |
Commanded velocity for the homing move |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit/sec |
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Default |
— |
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Acceleration |
Description |
Commanded acceleration for the homing move |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit/sec2 |
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Default |
— |
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Deceleration |
Description |
Commanded deceleration for the homing move |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit/sec2 |
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Default |
— |
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Description |
Commanded jerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time for the homing move (if zero, then trapezoidal acc/dec is used) |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit/sec3 |
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Default |
— |
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TorqueLimit |
Description |
Maximum torqueTorque is the tendency of a force to rotate an object about an axis. Just as a force is a push or a pull, a torque can be thought of as a twist applied for the homing move |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit entered in thousandths of maximum torque, e.g. "250" is 250/1000, or 25%. |
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Default |
— |
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TimeLimit |
Description |
Maximum time for homing move to complete. If exceeded the homing procedure will error out. 0= no time limit |
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Data type |
TIME |
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Range |
— |
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Unit |
sec |
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Default |
— |
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DistanceLimit |
Description |
Maximum distance for homing move to complete. If exceeded the homing procedure will error out. 0= no distance limit |
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Data type |
LREAL |
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Range |
— |
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Unit |
User unit |
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Default |
— |
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FastInputNum |
Description |
0 for first fast input (X7 Pin 10), 1 for second fast input (X7 pin 9) |
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Data type |
BOOL |
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Range |
[0 , 1] |
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Unit |
N/A |
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Default |
— |
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BufferMode |
Description |
Define the homing move start action
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Data type |
SINT |
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Range |
[0 , 5] |
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Unit |
N/A |
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Default |
— |
Output
Done |
Description |
Indicates the move completed successfully. The Command Position has reached the endpoint |
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Data type |
BOOL |
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Unit |
N/A |
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Busy |
Description |
High from the moment the Execute input is one-shot to the time the move is ended |
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Data type |
BOOL |
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Unit |
N/A |
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Active |
Description |
Set when the function block is active |
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Data type |
BOOL |
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Unit |
N/A |
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CommandAborted |
Description |
Indicates the move was aborted |
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Data type |
BOOL |
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Unit |
N/A |
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Error |
Description |
Signals that an error has occurred within the function block |
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Data type |
BOOL |
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Unit |
N/A |
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ErrorID |
Description |
Indicates the error if Error output is set to TRUE
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Data type |
INT |
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Unit |
N/A |
Usage
The homing is commanded in the most likely direction were the sensor can be found. In this example (-).
Related Functions
Example
Structured Text
Execute_1 :=1;
Inst_MCFB_StepLimitSwitchFastInput( Execute_1, Axis1, 0, 0, 10000.0, 10000.0, 10000.0, 0, 0, 0, 0, 0, 0);
HomeComplete := Inst_MCFB_StepLimitSwitchFastInput.Done;
HomeBusy := Inst_MCFB_StepLimitSwitchFastInput.Busy;
HomeActive := Inst_MCFB_StepLimitSwitchFastInput.Active;
HomeAborted := Inst_MCFB_StepLimitSwitchFastInput.CommandAborted;
HomeError := Inst_MCFB_StepLimitSwitchFastInput.Error;
HomeErrorID := Inst_MCFB_StepLimitSwitchFastInput.ErrorID;
FBD
Ladder Diagram