NORD Drivesystems BU0550 - Manual (Page 18)

PLC logic for NORD SK 54xE frequency inverters
18 BU 0550 GB-0813
2.5 PLC configuration
The PLC configuration dialogue is opened via the symbol. Here, basic settings for the PLC can be
made, which are described in further detail below.
Cycle time monitoring
This function monitors the maximum processing time for a PLC cycle. With this, unintended continuous
program loops in the PLC program can be caught. The time can be set in 5ms steps up to a maximum of 1
second. Error 22.4 is triggered in the frequency inverter if this time is exceeded.
Allow ParameterBox function module
This option must be activated (see Section 3.5.6) if visualisation via the ParameterBox is to be carried out in
the PLC program. Otherwise, the relevant function blocks generate a Compiler error when the frequency
inverter is started.
Invalid control data
The PLC can evaluate control words which are received from the possible bus systems. However, the
control words can only get through if the bit "PZD valid" (Bit 10) is set. This option must be activated if
control words which are not compliant with the USS protocol are to be evaluated by the PLC. Bit 10 in the
first word is then no longer queried.
Warm start after error
When the PLC starts, all variables are always loaded with "0" or their initialisation value. It does not matter
whether the start is performed after a stop, a program download or a PLC error.
With the option "Warm start after error the content of the variables is not changed for a warm start. A warm
start is performed after a PLC Stop command or a PLC error.
Do not pause the system time at holding point
The system time is paused during debugging if the PLC is in the holding point or in single step mode. The
system time forms the basis for all timers in the PLC.
This function must be activated if the system time is to continue running during debugging.
2.6 PLC program start
Execution of a PLC program in the frequency inverter can be started in several ways:

NORDCON: Activation of the symbol in the menu bar.

Parameter P350 setting 1 "On" - The program starts immediately after the control board of the
frequency inverter becomes ready for operation - e.g after the power supply is switched on.

In case of interruptions of the program by P420/P480 [-xx] setting 80 "PLC Stop": by resetting the
input.