Allen-Bradley Kinetix 5100 2198-E1004-ERS - Reading the Absolute Position with Communication

400 Rockwell Automation Publication 2198-UM004A-EN-P - October 2019
Chapter 14 Absolute Position Recovery
13. The DO.ABSW signal resumes at low after the servo drive receives the
DI.ABSE signal.
14. The host controller resumes communication after T
B
time.
15. Repeat step 1
.
16. If no error occurs, the host controller completes 80 bits (0 … 79) of the
handshake communication with the servo drive. DI4, DO2, and DO3
then resume their original functions.
Reading the Absolute Position with Communication
You can access the data of the absolute encoder through two communication
methods: instant access or parameter access.
Instant access refers to reading the motor's feedback position as soon as the servo
is powered on. When you set the status monitoring register 1 to the motor's
feedback pulse number [ID668 (P0.017) SystemVariableMonitor1Selection = 0],
you can access the motor's current position by reading ID663 (P0.009)
SystemVariableMonitor1Value.
Parameter access means the motor's position is temporarily stored in parameters.
Once you set ID108 (P0.049) EncoderDataUpdateConfiguration with
communication, the encoder's status, absolute position (cycle number), and pulse
number (or PUU) are stored in ID109 (P0.050) AbsSysStatus, ID110 (P0.051)
MultiTurnAbsPosition, and ID111 (P0.052) SingleTurnAbsPosition respectively.
You can choose to read the pulse number or PUU
through ID243 (P2.070) Bit 1. Even when the
motor is stopped, it still moves slightly forward
and backward. When you set ID108 (P0.049) to 1,
the encoder continues to read the exact position of
where the motor stops, without changing anything
else. However, when you set ID108 (P0.049) to 2,
the encoder updates the motor's current position
on the servo drive, which clears the position error.
For example, the motor's current position is 20000,
but it varies from 19999 to 20001.
If you send the command to read the motor's position when it stops at 20001, the
motor's position is updated to 20001. After all positions are updated in
ID109 (P0.050)…ID111 (P0.052), ID108 (P0.049) is automatically reset to 0.
IMPORTANT If the DI.ABSE signal is set low first, and then changed to high, but the
DO.ABSW signal does not return to high, it means that some other errors exist.
Check for the following possible warnings: A 060 absolute position lost, low
battery voltage level, or absolute position overflows. Restart a new
communication cycle after those errors have been cleared.