User Manual
Appendix C
GFK-1742F
Jan 2020
Position Feedback Devices
416
Set Position Command - Absolute Encoder Mode
The Set Position %AQ command functions the same way as in incremental encoder mode.
At the completion of the Set Position operation, Actual Position is set to the Set Position
value. The DSM314 internally calculates the encoder Absolute Feedback Offset needed to
produce the commanded Set Position value. This Absolute Feedback Offset is immediately
saved in the DSM314 non-volatile (capacitor backup) memory.
If a Set Position AQ command is received before the encoder has been referenced, Error
Code 53(hex) “Attempt to initialize position before digital encoder passes reference point”
will be reported. This error code is only reported if the Feedback Mode is set to Absolute.
Serial Encoders configured for Incremental mode do not have this restriction.
Once an absolute position is established by a Set Position command, the DSM314
automatically initializes Actual Position after a power cycle and sets the Position Valid %I bit.
C-3.3
Absolute Encoder Mode - DSM314 Power-Up
The battery pack attached to the servo subsystem maintains power to the encoder counter
logic. Once the encoder has referenced through first time start up, the encoder
automatically maintains the actual position, even if the axis is moved during servo power
loss. The encoder monitors the status of the battery pack, and reports loss of battery power
or low battery power to the DSM314.
The DSM314 completes a power-on diagnostic, and when configured for absolute encoder
mode, interrogates the referenced status of the Digital serial encoder. A valid referenced
status from the encoder signals the DSM314 to read the encoder absolute position. The
DSM314 reports the Actual Position %AI status as the sum of the encoder position and the
Absolute Feedback Offset established by the initial Find Home cycle or Set Position %AQ
command.