NORD Drivesystems BU0550 - Manual (Page 9)

1 General
BU 0550 GB-0813 9
1 General information
The NORD SK 54xE frequency inverter contains logic processing which is similar to the current IEC61131-3
standard for memory programmable control units (SPS / PLC). The reaction speed or computing power of
this PLC is suitable to undertake smaller tasks in the area of the inverter. Inverter inputs or information from
a connected field bus can be monitored, evaluated and further processed into appropriate setpoint values
for the frequency inverter. In combination with other NORD devices, visualisation of system statuses or the
input of special customer parameters is also possible. Therefore, within a limited range, there is a potential
for savings via the elimination of a previous external PC solution.
AWL is supported as the programming language. AWL is a machine-orientated, text-based programming
language whose scope and application is specified in IEC61131-3.
NOTE
Programming and download into the frequency inverter is exclusively via the NORD software
NORDCON.
1.1 Specification of the PLC
Function Specification
Standard Orientated to IEC61131-3
Language Instruction List ( IL )
Task A cyclic task, program call-up every 5 ms
Computer performance Approximately 200 AWL commands per 1 ms
Program memory 4032 Byte for flags, functions and the PLC program
Max. possible number of
commands approximately 1280 commands
Attention! This is an average value. Heavy use of flags, process data and
functions considerably reduces the possible number of lines, see the
"Resources" section
Freely accessible CAN
mailboxes 20
Table 1PLC specification
1.2 PLC structure
1.2.1 Memory
The PLC memory is divided into the program memory and the flag memory. In addition to the variables,
instances of function blocks are saved in the area of the flag memory. In instance is a memory area in which
all internal input and output variables of function command are saved. Each function command declaration
requires a separate instance. The boundary between the program memory and the flag memory is
determined dynamically, depending on the size of the flag area.
Fig. 1 Memory structure
Total memory
4032 Byte
Program memory Flag memory
Variables
Instances of
function commands