NORDAC SK 530E with PosiCon funktion
40
Subject to technical changes
BU 0510 EN
6 Synchronous
control
6.1 General
Synchronous control with the SK 530E can be implemented by coupling the devices via CAN bus. The master
device sends its "actual position" and "actual setpoint speed after frequency ramp" to the slave device(s). The slave
devices use this speed as the lead and synchronise the rest via the position control. The transmission time of
actual speed and position from the master to the slave devices generates an angle or position offset which is
proportional to the speed travelled.
Δ
P = n[rpm] / 60 * T
cycle
[ms] / 1000
At 1500 rpm and a transmission time of approx. 5ms, the offset is 0.125 revolutions or 45°. This offset is partially
compensated for by a corresponding compensation on the slave side. However a cycle time jitter of approx. 1ms
remains and this cannot be compensated. In the above case, an angle error of approx. 9° will remain. This only
applies when a CAN connection with a baud rate of at least 100 kBaud is used to couple the two drives. The offset
can be significantly larger when coupling via RS485 or with smaller CAN baud rates.
NOTE:
Coupling with smaller baud rates or USS is therefore not recommended.
The implementation of position synchronisation is also possible by coupling via CANopen. This enables operation
with CANopen absolute encoders and simultaneous coupling of several drives. With higher numbers of slave
encoders, it must be ensured that the maximum number of encoders does not exceed 5 so that the bus load
remains under 50% and deterministic behaviour is ensured.
6.2 Communication
settings
The following settings are required for communication between master and slave via
CAN
bus.
Master device settings:
P502[01]
=
20
Setpoint frequency after frequency ramp
P502[02]
=
15
Actual position Inc. High Word
P502[03]
=
10
Actual position Inc. Low Word
P503
=
2
CAN
P505
=
0
0.0 Hz
P514
=
5
250 kBaud (minimum 100 kBaud must be set)
P515
=
0
Address 0 (see monitoring)
Slave device settings:
P510[01]
=
9
Main setpoint of CAN – Broadcast
P510[02]
=
9
Auxiliary setpoint of CAN – Broadcast
P505
=
0
0.0 Hz
P514
=
5
250 kBaud (minimum 100 kBaud must be set)
P515[00]
=
128
Address 128 (see monitoring)
P546 = 4 Frequency
addition
P547
=
24
Setpoint position in Inc. High Word
P548
=
23
Setpoint position in Inc. Low Word
P600
=
1, 2
Position control ON with maximum frequency or On with setpoint frequency
7
P610 = 2 Synchronisation
7
Both variants are possible as the maximum positioning speed during synchronisation is always F
max
