Note: With a multiturn absolute encoder, bit 6 of 90.35 is cleared at the next stop of the
drive if the encoder has recovered from the error; bit 4 is not cleared. The status of the
position counter is retained over a control unit reboot, after which position calculation
resumes from the absolute position given by the encoder, taking into account the initial
position specified by 90.58.
WARNING!
If the drive is in stopped state when an encoder error occurs, or if the drive is not
powered, parameters 90.4, 90.5, 90.7 and 90.35 are not updated because no
movement of the load can be detected. When using previous position values
(90.60 is set to Continue from previous value), be aware that the position data is
unreliable if the load is able to move.
Reading/writing position counter values through fieldbus
The parameters of the position counter function, such as 90.7 and 90.58, can be
accessed from an upper-level control system in the following formats:
• 16-bit integer (if 16 bits are sufficient for the application)
• 32-bit integer (can be accessed as two consequent 16-bit words).
For example, to read parameter 90.7 through fieldbus, set the selection parameter of
the desired dataset (in group 52) to Other – 90.7, and select the format. If you select a
32-bit format, the subsequent data word is also automatically reserved.
Configuration of HTL encoder motor feedback
1.
Specify the type of the encoder interface module (parameter 91.11 = FEN-31) and
the slot the module is installed into (91.12).
2.
Specify the type of the encoder (92.1 = HTL). The parameter listing will be re-read
from the drive after the value is changed.
3.
Specify the interface module that the encoder is connected to (92.2 = Module 1).
4.
Set the number of pulses according to encoder nameplate (92.10).
5. If the encoder rotates at a different speed to the motor (ie. is not mounted directly
on the motor shaft), enter the gear ratio in 90.43 and 90.44.
6.
Set parameter 91.10 to Refresh to apply the new parameter settings. The parameter
will automatically revert to Done.
7.
Check that 91.2 is showing the correct interface module type (FEN-31). Also check
the status of the module; both LEDs should be glowing green.
8. Start the motor with a reference of eg. 400 rpm.
9.
Compare the estimated speed (1.2) with the measured speed (1.4). If the values
are the same, set the encoder as the feedback source (90.41 = Encoder 1).
58 Program features
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