Technical data

Table Of Contents
SFCs/SFBs for Transferring Data Records
System Software for S7-300/400 System and Standard Functions - Volume 1/2
7-2
A5E00709327-01
Write-Only System Data Area
The following table shows the structure of the write-only system data area. This
table also shows how long the data records can be and with which SFCs the data
records can be written.
Data Record
Number
Contents
Size
Restriction
Can be Written
with SFC
0 Parameters With S7-300:
from 2 to 14 bytes
Can only be
written
by an S7-400
56 "WR_DPARM"
57 "PARM_MOD"
1 Parameters With S7-300:
from 2 to 14 bytes
Data records 0 and 1 together
have a total of exactly 16 bytes.
- 55 "WR_PARM"
56 "WR_DPARM"
57 "PARM_MOD"
2 to 127 User data Each = 240 bytes - 55 "WR_PARM"
56 "WR_DPARM"
57 "PARM_MOD"
58 "WR_REC"
128 to 240 Parameters Each = 240 bytes - 55 "WR_PARM"
56 "WR_DPARM"
57 "PARM_MOD"
58 "WR_REC"
Read-only System Data Area
The following table shows the structure of the read-only system data area. This
table also shows how long the data records can be and with which SFCs the data
records can be read.
Data Record
Number
Contents
Size
Can be Read with
SFC
0 Module-specific diagnostic data
(set as standard for the whole
system)
4 bytes 51 "RDSYSST"
(SSL_ID 00B1H)
59 "RD_REC"
1 Channel-specific
diagnostic data
(including data record 0)
with S7-300: 16 bytes
with S7-400: 4 to 220
Bytes
51 "RDSYSST"
(SSL_ID 00B2H and
00B3H)
59 "RD_REC"
2 to 127 User data Each < 240 bytes 59 "RD_REC"
128 to 240 Diagnostic data Each < 240 bytes 59 "RD_REC"