Delta RMC101 - Manual (Page 589)

Quadrature with Stepper Output 6.4
Transducer Interface Modules 6-45
Note: If the Auto Home Re-arm configuration bit is cleared after the Arm Home command has
been issued, the axis will still be armed. However, once the axis is homed, it will not be
automatically re-armed.
When the axis is armed and there is a falling edge in the Home active, the exact quadrature
counts at the time of the falling edge are used as the physical home position. The Actual Position
will be changed to reflect the current position with respect to the home position as specified in the
Arm Home command. The Command Position and Target Position will be offset by the difference
between the new and old Actual Positions.
The Home Status bit in the Status word can be used to help home the system. It can be
configured with the Level/Edge bit in the Config word either to be latched on the falling edge of
the Home active condition or to match the level of the Home Active condition.
Linear Positioner Homing Hints
When using a quadrature encoder on a linear positioner, the axis must be homed to retain
absolute positions. This is easiest if the proximity switch controlling the H input to the axis is
placed at one end of the travel; this will be the home position. The Z input is not used (not
connected) and should be configured to be always active.
Set the Level/Edge bit in the Config word to Level of H input so that the status bit will be active
when the H input is active. Next, arm the axis’s homing by issuing an Arm Home command.
When starting from an unknown position, retract until the Home Status bit is ON. Then, extend
until the Home Status bit is OFF and stop. When the Level/Edge bit is set, the falling edge on the
Home Status bit indicates the axis has been homed.
If the axis is already retracted, the axis will see the Home Status bit ON immediately and extend
as described above. When the axis is shut down, it should be retracted until the Home Status bit
is ON. This way the axis need only extend a small amount to be homed on startup.
6.4 Quadrature with Stepper Output
6.4.1 Quadrature with Stepper Output Overview
The STEP interface module is one of two RMC interface modules with an interface for quadrature
encoder feedback. This module provides stepper drive output, while the QUAD interface module
provides analog drive output. Together, these modules allow the RMC100 series motion
controllers to control a wide range of motors and linear actuators with quadrature encoder
feedback. For details on the QUAD module, see Quadrature with Analog Output Overview.
Each stepper module can control two stepper axes, each with both stepper-motor and
quadrature-encoder interfaces.
The quadrature-encoder interface does not have to be used; the motor can be controlled in open
loop and still take advantage of the RMC’s host of target generating methods including
trapezoidal and s-curve point-to-point moves, gearing, synchronization, and splines.
When used with quadrature feedback, faults can be triggered on following errors, and motor
compensation can be enabled. See Stepper Compensation for details on this feature.
Features