Chapter 6 Communication Mode
6 - 51
Mod
b
u
s S
lav
e
I/O mapping function
The I/O mapping function was supported from software ver. 2.0.
If an I/O mapping function is used, arbitrary I/O classification and addresses can be assigned to the address to
H0000 - HFFFF. (The table after address translation is called mapping table.)
Two mapping tables (for bits, for words) can be set up.
Figure 6.50 I/O mapping image
« Note »
Be careful of the following point at the time of I/O mapping functional use.
The function codes 01 (Read Coil Status) and 02 (Read Input Status) turn into a code of the same purpose.
The function codes 03 (Read Holding Registers) and 04 (Read Input Registers) turn into a code of the same
purpose.
An input (Input) and an output (Coil) are intermingled in an address H0000 - HFFFF. The set to an input and a N
continuation set come be made, the data set to the input is updated by the actual input value by I/O refreshment.
N continuation read or N continuation set cannot be performed ranging over I/O from which classification differs.
Reference : Merit / demerit of the I/O mapping
(1) Merit
Since I/O which can be accessed in function code was decided as shown in Table 6.14, EH-SIO cannot be accessed
at I/O which does not correspond to a function code.
Moreover, although the address of I/O is specified by 1-word data (H0000 - HFFFF) in a Modbus protocol, since
the number of the addresses of remote I/O of EH-150 is five, they cannot be accessed by the Modbus protocol.
These problems are solved by using an I/O mapping function.
(2) Demerit
Since I/O of two or more classifications is made intermingled in an address H0000 - HFFFF, a user needs to
manage the assigned address. A host has to send query conscious of I/O mapping.
Ex.) When WR0 is mapped in H8000
For accessing WR2000, it is specified as an address HA000.
Coil
Input
Holding
Register
Input
Register
H0000
HFFFF
H0000
HFFFF
H0000
HFFFF
H0000
HFFFF
H0000
HFFFF
H0000
HFFFF
Word
Bit
Mapping table
Modbus
X
Y
R
M
WR
WL
WM
EH-SIO
Default
Y
X
WR
WM
Summary of Contents for EH-150 Series
Page 2: ......
Page 10: ...M E M O ...
Page 30: ...Chapter 4 Installation 4 10 M E M O ...
Page 156: ...Chapter 7 System setup 7 12 M E M O ...
Page 164: ...Chapter 8 Daily and Periodic Inspection 8 8 M E M O ...