I/o buffer and data mapping, Mapping method of the i/o buffer, Data count and data type – Yokogawa Removable Chassis DX1000N User Manual
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I/O Buffer and Data Mapping
A master device such as a PLC accesses internal data of the DX via the "Input buffer"
and "Output buffer" of the DX. "Input" represents an input to the master, while "Output"
represents an output from the master.
Mapping Method of the I/O buffer
The "Input buffer" and "Output buffer" of the DX for PROFIBUS-DP communication has
128 bytes each. Data is laid out as described in the following table. Data layout cannot
be changed.
Buffer
Application
Description
Input
Reading
measurement channel
data and computation
channel data
Locates all the measurement channel data from the top of
the buffer. Locates as much computation channel data as
possible in the remaining part of the buffer.
Buffer
Application
Description
Output
Writing
communication input
data
Locates as much communication input data as possible.
Data Count and Data Type
The DX data count is as follows:
Model
Measurement channel
Computation channel
Communication input
data
Count
Number
Count
Number
Count
Number
DX002
2
00, 002
2
0 to 2
24
C0 to C24
DX004
4
00 to 004
DX1006
6
001 to 006
24
0 to 24
DX02
2
00 to 02
DX2004
4
00 to 004
2
0 to 2
60
C01 to C32
(C33 to C60)
*
DX2008
8
001 to 008
DX200
0
00 to 00
60
0 to 27
(128 to 160)
*
DX2020
20
00 to 020
0 to 22
(123 to 160)
*
DX2030
30
001 to 030
0 to 7
(118 to 160)
*
DX2040
40
00 to 040
0 to 2
(113 to 160)
*
DX2048
48
001 to 048
101 to 108
(109 to 160)
*
*1 Data in parentheses cannot be located in a buffer because it exceeds the capacity of the I/O
buffer.
Note
The communication input data for C01 to C24 (on the DX1000) or for C01 to C32 (on the
DX2000) is reserved for PROFIBUS-DP.
You cannot write to these data numbers through other means (such as Modbus, EtherNet/IP, or
communication commands).