Continue from previous value, the position values are retained over an error or
reboot; bit 6 of 90.35 is set however to indicate that an error occurred.
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.
96 Program features
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