NORD Drivesystems BU0550 - Manual (Page 11)

1 General
BU 0550 GB-0813 11
1.2.4 Setpoint processing
The inverter has a variety of setpoint sources, which are ultimately linked via several parameters to form a
frequency inverter setpoint.
Fig. 3 Generation of control word and main setpoints from a range of possible sources
If the PLC is activated (P350=1) preselection of setpoints from external sources (main setpoints) is carried
out via P509 and P510[-01] Via P351, a final decision is made as to which setpoints from the PLC or values
input via P509/P510[-01] are used. A mixture of both is also possible.
No changes to the auxiliary setpoints (P510[-02]) are associated with the PLC function. All auxiliary setpoint
sources and the PLC transfer their auxiliary setpoint to the frequency inverter with equal priority.
1.2.5 Data processing via accumulator
The accumulator forms the central computing unit of the PLC. Almost all AWL commands only function in
association with the accumulator. The NORD PLC has three accumulators. These are the 23 Bit Accumula-
tor 1 and Accumulator 2 and the AE in BOOL format.
The AE is used for all boolean loading, storage and comparison operations. If a boolean value is loaded, it is
displayed in the AE. Comparison operations transfer their results to the AE and conditional jumps are
triggered by the AE.
Accumulator 1 and Accumulator 2 are used for all operands in the data format BYTE, INT and DINT.
Accumulator 1 is the main accumulator and Accumulator 2 is only used for auxiliary functions. All loading
and storage operands are handled by Accumulator 1. All arithmetic operands save their results in
Accumulator 1. With each Load command, the contents of Accumulator 1 are moved to Accumulator 2. A
subsequent operator can link the two accumulators together or evaluate them and save the result in
Accumulator 1, which in the following will generally be referred to as the "accumulator".
CAN /CANopen
USS
TU3_xxx
Local
PLC
Cycle 5ms
P509 &
P510[1]
Cycle 1 ms
P350
P350=0
P350=1
P351
Setpoint