NORD Drivesystems BU0210 - Manual (Page 45)

6 Synchronous control
BU 0210 GB Subject to technical amendments 45
6 Synchronous control
6.1 General information
The implementation of synchronous positioning with the SK 2X5E is possible by coupling the devices via the
system bus. The master device transmits its "Actual Position" and its "Actual Setpoint Speed After the
Frequency Ramp" to the slave device(s). The slave devices use the speed as specified and compensate the
remainder via the position control. The transmission time for the actual speed and position from the master to
the slave devices generates an angular or positional deviation which is proportional to the speed of travel.
ΔP = n[rpm] / 60 * T
zyklus
[ms] / 1000
With 1500 rpm and a transmission time of approx. 5ms, a deviation of 0.125 rotations or 45° results. This
deviation is to some extent adjusted for by an appropriate compensation by the slave. However, there is still a
jitter of approx. 1ms in the cycle time, which cannot be compensated for. In the case selected, there remains
an angular error of approx 9°. This only applies if a system bus connection with a baud rate of at least
100kBaud is used to couple the two drive units. For couplings with a lower baud rate, the deviation can be
considerably greater.
NOTE: A coupling with low baud rates is therefore not advisable.
With a system bus coupling, operation with CANopen absolute encoders and the simultaneous coupling of
several drive units is possible. For large numbers or slave inverters, it should be noted that the maximum
number of inverters should not exceed 5, in order that the bus load remains below 50% and therefore a
deterministic behaviour is ensured.
6.2 Communication settings
In order to set up a communication between the master and the slave via the system bus the following
settings are necessary.
Master device settings:
P502[01]
= 20 Setpoint frequency after the frequency ramp
P502[02] = 15 Actual position in incremental High word
P502[03] = 10 Actual position in incremental Low word
P503 = 1 CANopen
P505 = 0 0.0 Hz
P514 = 5 250 kBaud (at least 100 kBaud should be set)
P515[02] = P515
Slave
[01] Broadcast – Master – Address
Slave device settings:
P510[01]
= 10 Main setpoint value of CANopen - Broadcast
P510[02] = 10 Subsidiary setpoint value of CANopen - Broadcast
P505 = 0 0.0 Hz
P514 = 5 250 kBaud (at least 100 kBaud should be set)
P515[01] = P515
Master
[02] Broadcast - Slave - Address
P546 = 4 Frequency addition
P547 = 24 Setpoint position in incremental High word
P548 = 23 Setpoint position in incremental Low word
P600 = 1, 2 Position control ON with maximum frequency or ON with setpoint frequency 8
P610 = 2 Synchronous operation
NOTE: The actual position of the master must always be transmitted to the slave in the setting "In
Increments" and be evaluated by the slave, as otherwise an additional transmission time error
would be created.
8 Both variants are possible, as with synchronous operation the maximum positioning speed is always F
max
.