46 Program features
Parameter 90.60 Pos counter error and boot action defines whether position
calculation resumes from the previous value over an encoder error or control unit
reboot. By default, bit 4 of 90.35 Pos counter status is cleared after an error,
indicating that reinitialization is needed. With 90.60 set to 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 90.07 and 90.35 are not updated
because no movement of the load can be detected. When using previous position
values (90.60 Pos counter error and boot action 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 90.07 Load position scaled
int and 90.58 Pos counter init value int, 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 90.07 Load position scaled int through fieldbus, set
the selection parameter of the desired dataset (in group 52) to Other – 90.07, 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 Module 1 type
= FEN-31) and the slot the module is installed into (91.12 Module 1 location).
2. Specify the type of the encoder (92.01 Encoder 1 type = 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 (92.02 Encoder 1
source = Module 1).
4. Set the number of pulses according to encoder nameplate
(92.10 Pulses/revolution).
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 Motor gear numerator and
90.44 Motor gear denominator.
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