Handling Data Records; Writing/Reading Data Records - Siemens SIMOCODE pro System Manual

B.1

Handling data records

This section contains helpful information about how best to handle data
records.
B.1.1

Writing/reading data records

Access to data records via slot and index
• Slot: Access via slot 1
• Index: Data record number
Writing/reading data records with STEP 7
You can access the data records from the user program.
• Writing data records:
S7 DPV1 master: By calling SFB 53 "WR_REC" or SFC 58
S7 master:
• Reading data records:
S7 DPV1 master: By calling SFB 52 "RD_REC" or SFC 59
S7 master:
Further information
You will find further information on the SFBs:
• In the "System Software for S7-300/400, System and Standard Functions"
reference manual
• In the STEP7 online help.
Byte arrangements
When data which is longer than one byte is saved, the bytes are arranged as
follows ("big endian"):
Byte arrangement
Byte 0
Byte 1
Byte 2
Byte 3
Byte 0
Byte 1
Byte 0
Byte 1
Fig. B-1: Byte arrangement in "big endian" format
SIMOCODE pro
GWA 4NEB 631 6050-22 DS 03
By calling SFC 58
By calling SFC 59"
High byte
High word
Low byte
High byte
Low word
Low byte
High byte
Low byte
Byte 0
Byte 1
Data formats and data records
Data type
Double word (D-word)
Word
Byte
B-3