Example Of An Address Area Configuration For Transfer Memory - Siemens SIMATIC S7-300 Series Reference Manual

Address areas of the transfer memory
Configure the I/O address areas in STEP 7:
S you can configure up to 32 I/O address areas
S the maximum length of each one of these address areas is 32 bytes
S You can configure a maximum of 244 bytes for inputs and 244 bytes for
outputs.
The table below shows the principle of address areas. You can also find this figure
in the STEP 7 configuration.
Table 2-5

Example of an address area configuration for transfer memory

Typ
e
1 E
2 A
:
32
Address areas in the
DP Master CPU
Rules
The following rules must be followed when using the intermediate memory:
S Address area assignment:
– Input data of the DP slave are always output data of the DP master
– Output data of the DP slave are always input data of the DP master
S The addresses can be freely allocated. In the user program, access the data
with Load/Transfer statements or with SFCs 14 and 15. You can also specify
addresses from the I/O process images.
Note
Transfer memory addresses are assigned from the DP address area of the CPU
31x-2.
Do not assign transfer memory addresses to the I/O modules in the CPU 31x-2!
S The lowest address represents the start address of the respective address
area.
S Length, unit and consistency of DP Master/Slave address areas related to each
other must be identical.
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
CPU 31x-2 as DP Master/DP Slave and Direct Communication
Master Typ Slave
Address e Address
222 A 310
0 E 13
Address areas in the
DP Slave CPU
Lengt Unit Consistenc
h
2 Byte Unit
10 Word Total length
These address area parameters
must be the same for both the DP
Master and DP Slave
y
2-15