Technical data

Table Of Contents
S7 Communication
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
21-51
21.18 Work Memory Requirements of the S7 Communication
SFBs/FBs
To function smoothly, the S7 communication SFBs/FBs require a temporary
memory area within the CPU work memory dependent on the user data (code
area). The size of the occupied memory is shown in the following table:
Block inS7-300 Required Memory in the Working Memory in Bytes
FB 8
USEND
Block: 4583 bytes, Instance: 368 bytes
FB 9 URCV Block: 4880 bytes, Instance: 370 bytes
FB 12 BSEND Block: 5284 bytes, Instance: 372 bytes
FB 13 BRCV Block: 5258 bytes, Instance: 374 bytes
FB 14 GET Block: 4888 bytes, Instance: 336 bytes
FB 15 PUT Block: 4736 bytes, Instance: 384 bytes
FC 62 C_CNTRL Block: 546 bytes
Note on Interruption Behavior
In, S7-300, SIMATIC_NET communication blocks may only be called in one priority
class.
Block in S7-400 Required Memory in the Working Memory in Bytes
SFB 8/
SFB 9
USEND/
URCV
68 + Length of the indicated user data when first called up from SD_1,...
SD_4/RD_1,... RD_4
SFB 12/
SFB 13
BSEND/
BRCV
54
SFB 14 GET 88 + Length of the indicated user data when first called up from RD_1,...
RD_4
SFB 15 PUT 108 + Length of the indicated user data when first called up from SD_1,...
SD_4
SFB 16 PRINT 78 + Length specification of FORMAT + Length of the specified user data
when first called up from SD_1,... SD_4
SFB 19 START 52 + Length of the indicated parameter when first called up from
PI_NAME and ARG.
SFB 20 STOP 48 + Length of the indicated parameter when first called up from
PI_NAME.
SFB 21 RESUME 52 + Length of the indicated parameter when first called up from
PI_NAME and ARG.
SFB 22 STATUS 50
SFB 23 USTATUS 50