Table 5: Ndb Structure; Table 6: Configuration Of Read/Write Commands - Siemens SIMATIC NET CP 243-1 Technical Manual

Configuration
Byte offset in
variables memory
... COM_CHr_OFF
... COM_CHr_LEN0
... ...
... COM_CHr_LENp
... COM_CHr_0
... ...
... COM_CHr_p
CRC section
The last two bytes CRC over all NDB
of the NDB bytes without the
CRC section itself

Table 5: NDB structure

Name
<op> Command type
Value range: "R" for a "read",
<cnt> Number of bytes to be transmitted
Value range: "1" to "212"
<local_buffer> Address of memory area in local system
Value range:
<remote_buffer> Address of memory area in communication partner
Value range:

Table 6: Configuration of read/write commands

44
Name
2 bytes hex
Description
"W" for a "write"
"VB0" to "VBx", where x is the max. V address
"IB0" to "IBx", where x is the max. input address
(S7-200 / S7-300 / S7-400)
"QB0" to "QBx", where x is the max. output address
(S7-200 / S7-300 / S7-400)
"MB0" to "MBx", where x is the max. flag address
(S7-200 / S7-300 / S7-400)
"VB0" to "VBx", where x is the max. variables address
(S7-200)
"DB0.DBB0" to "DBx.DBBy", where x is the max. DB
number,
y is the highest address in the corresponding data block
within the DB (S7-300 / S7-400)
Description
J31069-D0428-U001-A1-7618
09/02
Data
format
1 byte hex
1 byte hex
1 byte hex
1 byte hex
ASCII
ASCII
ASCII
The last two
bytes of the
NDB
Data
format
ASCII
ASCII
ASCII
ASCII
CP 243-1