4. Configuration
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ï‚· If the CPU aborted the event generation (because occurred to more events in a single execution
cycle than the events queue total size)
Producers
The producers are tipically communication drivers or PLC internal elements that are capable to
generate events. The previous figure show some examples.
 Internal Points: This is an PLC’s firmware internal element, which detecs events each execution
cycle (MainTask) to those communication points that don’t have a defined origin and then inserts
the events in the CPU’s queue. The maximum number of events that can be detected in each
MainTask cycle is equal to the CPU’s events queue size. In case the number of generated events
is bigger than this, in a single cycle, the exceeding are going to be lost.
ï‚· MODBUS Driver (Client/Server/Master/Slave): the variables value change caused by MODBUS
read/write are detected at each MainTask cycle and then the events are inserted in CPU’s queue.
In Client/Master cases, are also generated quality events when there is a communication falure
with the slave device.
Interception of Commands Coming from the Control Center
The Nexto PLC has a function block that allows selection commands and operation to the output
points received by server drivers (Server IEC 60870-5-104) been treated by the user logic. This
resource allows the interlocking implementation, as well as the handling of the received command
data in the user logic, or yet the command redirecting to different IEDs.
The commands interception is implemented by the CommandReceiver function block, defined in the
LibRtuStandard library. The input and output parameters ae described on the following tables:
When TRUE, execute the command interception
Indicates that the command output data have been already
processed, releasing the function block to receive another
command.
Variable address, mapped in the server driver, which will
receive the client command.
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General