Demand Data Structure - Mitsubishi 2404f User Manual

Demand Data
Demand Data uses the first 8 bytes in both the request and response message of the cyclic Data Exchange.

DEMAND DATA STRUCTURE

Read Request (from PLC)
PLC Output Register
Number
The first four registers are reserved for demand data.
The control program is responsible for writing values into
these first four registers to make requests.
1 Command Code and Parameter
Tag
2 Extended Parameter Tag
3 Reserved
4 Anything
The registers that follow are used for the fixed output
data defined by the GSD file
5 Value or State
6 Value or State
7 Value or State
etc. Value or State
Write Request (from PLC)
PLC Output Register
Number
The first four registers are reserved for demand data.
The control program is responsible for writing values into
these first four registers to make requests.
1 Command Code and Parameter
Tag
2 Extended Parameter Tag
3 Reserved
4 Value or State to be written
The registers that follow are used for the fixed output
data defined by the GSD file
5 Value or State
6 Value or State
7 Value or State
etc. Value or State
7-2
2408 f & 2404 f PROFIBUS Communications Handbook
Response to Read Request (from Controller)
Output Data PLC Input Register Number
The first four registers are reserved for responses to
demand data.
The registers that follow are used for the fixed input data
defined by the GSD file
Response to Write Request (from Controller)
Output Data
The first four registers are reserved for responses to
demand data.
The registers that follow are used for the fixed output
data defined by the GSD file
2408 f & 2404 f PROFIBUS Communications Handbook
1 Command Code and Parameter
Tag
2 Extended Parameter Tag
3 Reserved
4 Returned value
5 Value or State
6 Value or State
7 Value or State
etc. Value or State
PLC Output Register
Number
1 Command Code and Parameter
Tag
2 Extended Parameter Tag
3 Reserved
4 Write error code
5 Value or State
6 Value or State
7 Value or State
etc. Value or State
Input Data
Output Data