Rockwell Automation Publication 520-UM001I-EN-E - July 2016 225
Encoder/Pulse Train Usage and Position StepLogic Application Appendix E
Bit 3 “Drive Homed” indicates whether the drive has been homed since
power-up. This bit will be active once the drive has been homed either
manually or automatically. It will remain active until the next power down.
Use Over Communications
If 8 steps are not adequate for the application or if dynamic program changes are
required, many of the positioning functions can be controlled through an active
communication network. The following parameters will allow this control.
C121
[Comm Write Mode]
Repeated writes to parameters over a communication network can cause damage
to the drive EEPROM. This parameter allows the drive to accept parameter
changes without writing to the EEPROM.
C122
[Cmd Stat Select]
Selects velocity-specific or position/fibers-specific Command and Status Word
bit definitions for use over a communication network.
A560
[Enh Control Word]
This parameter allows many of the positioning functions to be completed
through parameter control using an explicit message. This allows the operation
over communications instead of with hardware inputs. The bits have the same
functions as the digital input options of the same name. Options relating to
positioning are:
Bit 0 “Home Limit” indicates the drive is at the home position.
Bit 1 “Find Home” causes the drive to find home at the next start
command. Deactivate this bit after completing the homing routine.
Bit 2 “Hold Step” overrides other inputs and causes the drive to remain at
its current step (running at zero speed once it reaches its position) until
released.
Bit 3 “Pos Redefine” resets the home position to the current position of
the machine. Deactivate this bit after completing the homing routine.
Bit 4 “Sync Enable” holds the existing frequency when A571 [Sync Time]
is set to enable speed synchronization. When this bit is deactivated the
drive will accelerate to the new commanded frequency based on A571
[Sync Time].
Bit 5 “Traverse Dis” disables the traverse function when this bit is active.
Parameter values set prior to setting 1 “RAM only” are saved in RAM.
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