NORD Drivesystems BU0510 - Manual (Page 62)

POSICON position control for NORD frequency inverters, SK 530E and above
62 Subject to technical alterations BU 0510 GB-3911
6 Synchronous control
6.1 General information
The implementation of synchronous positioning with the SK 530E is possible by coupling the devices via the
CAN 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 CAN connection with a baud rate of at least 100kBaud is
used to couple the two drive units. For couplings via RS485 or lower CAN baud rates, the deviation can be
considerably greater.
NOTE: A coupling with lower baud rates or USS is therefore not advisable.
Implementation of synchronisation is also possible with a CANopen coupling. This also enables operation with
CANopen absolute encoders and the simultaneous coupling of several drive units. 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 communication between the master and the slave via the CAN bus the following settings are
necessary.
Master device settings:
P502[-01]
= 20 Setpoint frequency after the frequency ramp
10
P502[-02] = 15 Actual position in incremental High word
P502[-03] = 10 Actual position in incremental Low word
P503 = 2 CAN
P505 = 0 0.0 Hz
P514 = 5 250 kBaud (at least 100 kBaud should be set)
P515[-01] = 0 Address 0 (see monitoring)
Slave device settings:
P510 [-01]
= 9 Main setpoint value of CAN - Broadcast
P510 [-02] = 9 Subsidiary setpoint value of CAN - Broadcast
P505 = 0 0.0 Hz
P514 = 5 250 kBaud (at least 100 kBaud should be set)
P515[-01] = 128 Address 128 (see monitoring)
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
11
P610 = 2 Synchronous operation
10
If the enable signal is not also transferred from the master to the slave device, i.e. the slave is only enabled in one direction but the
master rotates in both directions, the function " Actual frequency without slip master value"“ „21“ must be used instead of "Setpoint
frequency after frequency ramp" "20".
11 Both variants are possible, as with synchronous operation the maximum positioning speed is always F
max
.