NORDAC SK 530E with PosiCon function
14
Subject to technical changes
BU 0510 EN
3.2.2.1 Resetting the CANopen absolute encoder
Using the two functions "Reference point run" (see Chapter 3.2.1.1) and "Reset Position" (see Chapter 3.2.1.2), a
CANopen absolute encoder can also be run to the value "0" or the value set in parameter P609 [02] "Offset actual
position".
As resetting the position in the CANopen absolute encoder takes somewhat longer than the resetting of an
incremental encoder, the speed during the resetting procedure should be selected as low as possible, otherwise
greater variances can occur.
If both an incremental encoder and a CANopen absolute encoder are attached to the frequency inverter, both
encoders will be reset when the function "Reference point run" or "Reset position" are carried out.
3.2.2.2 Settings in the CANopen absolute encoder
The baud rate and CAN address must be set in the encoder. For the encoder switch assignments, please refer to
the operating instructions of the manufacturer.
The CAN address for the absolute encoder must be set according to the following formula in parameter P515 "CAN
address":
Encoder CAN address = SK 530E CAN bus address (P515) +
1
The CAN baud rate set in the encoder must be identical to that in the SK 530E parameter P514 "CAN bus baud
rate" and all other participants in the bus system.
If the encoder is parameterised via the SK 530E, the transmission cycle for the absolute encoder position is also
specified via the baud rate.
When operating several CANopen absolute encoders on a bus system, e. g. during synchronous operation,
different transmission cycles can be set for the CAN Master and the CANopen absolute encoders.
The cycle time can be parameterised with the parameter P552 "CAN cycle time" in Array [01] for the
CAN/CANopen master mode and in Array [02] for the CANopen absolute encoders. It must be ensured that the
parameterised values do not undershoot the value in the column minimum value of the actual cycle time. This value
is dependent on the baud rate set in the parameter P514 "CAN baud rate".
P514
Baudrate
[kBaud]
P552 [01]
Default CAN
Master
[ms]
P552 [02]
Default CANopen
absolute encoder
[ms]
P552 [02]
Minimum value for
actual cycle time
[ms]
Bus load caused by
an encoder
[%]
10 50 20 10 42.5
20 25 20 10 21.2
50 10 10 5 17.0
100 5 5 2 17.0
125 5 5 2 13.6
250 5 2 1 17.0
500 5 2 1 8.5
1000
1
5 2 1 4.25
Table 1
: Cycle time of encoder dependent on baud rate
The possible bus load for the system always depends on the system-specific real time. Very good results are
obtained with a bus load less than 40%. A bus load greater than 80% should not be selected in any case. When
estimating the bus load, the other possible bus traffic (setpoint and actual values for the FI's and other bus
participants) should be taken into account.
Additional information about the CAN interfaces can be found in the manual BU 0060.
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Only for test purposes, safe operation cannot be guaranteed.
