Basics
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1.1 Operands
In FPWIN Pro the following operands are available:
in- and outputs (X/Y) as well as internal memory areas
internal relays
special internal relays
timers and counters
data registers
special data registers
file registers
link registers and relays
The number of operands which are available depends on the PLC-type and its configuration. To see how many
of the respective operands are available, see your hardware description.
1.1.1 Inputs/Outputs
The amount of inputs/outputs available depends on the PLC and unit type. Each input terminal corresponds to
one input X, each output terminal corresponds to one output Y.
In system register 20 you set whether an output can be used once or more during the program.
Outputs which do not exist physically can be used like flags. These flags
are non-holding, which means their contents will be lost, e.g. after a
power failure.
1.1.2 Internal Relays
Internal Relays are memory areas where you can store interim results. Internal relays are treated like internal
outputs.
In system register no. 7 you define which internal relays are supposed to be holding/non-holding. Holding
means that its values will be retained even after a power failure.
The number of available internal relays depends on the PLC type (see hardware description of your PLC).
1.1.3 Special Internal Relays
Special internal relays are memory areas which are reserved for special PLC functions. They are automatically
set/reset by the PLC and are used:
to indicate certain system states, e.g. errors
as an impulse generator
to initialize the system
as ON/OFF control flag under certain conditions
such as when some flags get a certain status if data are ready for transmission in a PLC network.
The number of special internal relays available depends on the PLC type (see hardware description of your
PLC).
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