Appendix
A.4 Required memory for function blocks
Function blocks Instance 1  Instance 2

Note
OT
64

64


PM
72

56

+8 per support point
PO
96

96


PW
48

48


PT
40

40


RC
76

–


RE
128

112

+32 per record
as soon as a flag is used in the recipe, this
applies to every constant used in that recipe:
+4 per constant;
SC
20

–


SR(BIT)
96

96


SR(DWORD)
96

96


ST
24

–


T
52

52


TB
112

112


TC
76

76


VC
48

48


WT
84

84

+4 per channel
YT
96

96

+4 per channel
1) As soon as an interrupt module is used, +12 bytes of memory are required once
Required memory when connecting function blocks, using CP, T, D as an example
In order to estimate the required memory for a connected function block in LD/FBD,
you can assume a required memory space of eight bytes for each connected func-
tion block input and function block output. This applies regardless of whether the
function block inputs and/or outputs are digital or analog and of whether the con-
nection involves MB marker bytes or MD marker double words.
Depending on the complexity of the pre-wiring, the actual consumption can also be
higher. Each numerical constant used requires an additional 4 bytes in all pro-
gramming methods.
In EDP, each rung occupies 20 bytes, regardless of its content, while an input / output
circuit in the block diagram does not require any additional memory.
The following information was determined using the LD/FBD programming language.
CP - Comparator Connected to

Memory Required
Function block input-
s/outputs
Operand

bytes
CP (not connected)
  35
EN
I1

7
I1
IA1

7
I2
IA2

7
LT
Q1

7
Tab. 147: Memory Required FB CP
832
easyE402/24 MN050009ENEaton.com
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