YOKOGAWA FA-M3V e-RT3 Plus, Hardware Manual

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Appx. A1-6
IM 34M06C11-01E
Appendix A1.3 Restrictions due to the Size of
Data Area
Determine the total size M of the data area provided by all I/O modules (i.e., modules
excluding the power supply and CPU modules). Then check that the value of M
complies with restrictions placed by the maximum size of data area. The total size of
data area M varies depending on the order in which I/O modules are installed. Consider
system configuration in advance, including the number of subunits, unit number and I/O
modules’ installation locations, according to your application needs.

Restrictions due to the size of data area are defined as
M

112 + 32

(4 - n), where n = the number of CPU modules.
The values 112 and 32 here are the limits due to the function specifications of the CPU
modules.

Calculation Procedure
Sum up the sizes of data areas in sequence for all I/O modules, starting from slot 1 of
the main unit up to slot 16 of the 7th subunit to determine the total size M. If there is any
I/O module with a data-area size of 4, 8 or 16, then round up the running total for the
data area sizes to the nearest multiple of 4, 8 or 16 before you add the size of that I/O
module.
Example:
If the system is configured with the following modules, the total data area M is 56.
F
3
P
U
2
0
F
3
S
P
2
5
F
3
B
P
2
0
F
3
X
D
6
4
F
3
Y
D
6
4
F
3
A
D
0
4
F
3
D
A
0
2
F
3
N
C
1
2
F
3
C
T
0
4
F
3
L
E
0
1
F
3
R
S
2
2
F
3
L
C
5
1
F
3
L
P
0
2
2
2
0
0
2
4
2
6
4
12
16
32
8
34 48
2
56
0
0
0
0
0
0
8 Data‐area size:
Cumulative size of data area:
(1) (2) (3)
FAAP0102.VSD
(1) Calculation for an I/O Module with Data-area Size of 4
Round up the running total for the data-area sizes to the nearest multiple of 4, and then
add 4.
In this example, round up 6 to 8, and then add 4 to obtain 12.
(2) Calculation for an I/O Module with Data-area Size of 16
Round up the running total for the data-area sizes to the nearest multiple of 16, and then
add 16.
In this example, round up 12 to 16, and then add 16 to obtain 32.
(3) Calculation for an I/O Module with Data-area Size of 8
Round up the running total for the data-area sizes to the nearest multiple of 8, and then
add 8.
In this example, round up 34 to 40, and then add 8 to obtain 48.
Note
The total size of data area M varies depending on the order in which modules are
installed. If the initial system configuration fails to comply with any given restriction, try
changing the order in which modules are installed by serially installing I/O modules of
the same data-area size, for example. This strategy may achieve compliance with the
restriction.