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7 FBD/LD LANGUAGE
7.1 Configuration
■The input/output point of a function
• It is necessary that all the input points of a function should be connected to other FBD units over connecting wires.
• The data types of the input variables and output variables of a function should be of certain types. It is necessary that the
FBD units to be connected to the input point or output point should be of the same data types.
• Connect a variable element between an output variable (except for ENO) of a CPU module instruction or module dedicated
instruction and an input variable of another function (or function block).
• In a program that connects a function with EN to another function over a connecting wire, the other function must be a
function with EN and the program must connect ENO and EN over a connecting wire, in order to prevent the function from
using an indefinite value.
■When the step relay (S) or SFC block device (BL) is used
If the step relay (S) or SFC block device (BL) is used as a variable element, a conversion error may occur. If an error occurs,
change the variable element to a contact element.
The following is the example of rewriting.
In addition, to use the digit-specified step relay (S) or the step relay with block specification (BL\S), the data size must be
specified correctly. Since the step relay (S) and the step relay with block specification (BL\S) are not targeted for auto data
type conversion, a conversion error may occur if the data size are not the same.
The following is the example of rewriting.
Before change After change
Before change After change
AND_E
EN
IN1
IN2
ENO
AND_E
EN
IN1
IN2
ENO
BOOL_OUT_DATA1
BOOL_EN_DATA
bLabel1
bLabel2
bLabel3
(1)
(1) Connect ENO and EN over a connecting wire.
D0: UDK4S0
16 bit 32 bit
D100BL1\K4S10
32 bit
16 bit
TRUE
DMOV
EN
S
ENO
d
D0K4S0
16 bit 16 bit
D100: UDBL1\K8S10
32 bit
32 bit
TRUE
DMOV
EN
S
ENO
d