Siemens NCM S7 - Structure of FETCH Frames

Linking to Other Systems with FETCH/WRITE
213
SIMATIC NET NCM S7 for Industrial Ethernet
C79000-G8976-C129–06
a) Structure of FETCH Frames
The meaning and values of parameters shown without values in the following table
can be found in the section “Parameter Values“.
FETCH request frame FETCH response frame
0
System ID
=”S” 0 System ID =”S”
1 =”5” 1 =”5”
2
Length of header
=16d. 2 Length of header =16d.
3
ID OP code
=01 3 ID OP code =01
4
Length OP code
=03 4 Length OP code =03
5
OP code
=05 5 OP code =06
6
ORG field
=03 6 Ack field =0Fh
7
Length ORG field
=08 7 Length ack field =03
8
ORG ID
8 Error field =No
9
DBNR
9 Empty field =FFh
A
Start address
High Byte A Length empty field =07
B Low Byte B
C
Length
High Byte C
D Low Byte D free
E
Empty field
=FFh. E
F
Length empty field
=02 F
Data up to 64 K but
only if Error no. =0