Siemens SIMATIC S7 - 4 Data Communication with the PLC; Organization of the Dual Port RAM

4-1
SM 338 Equipment Manual
(4) J31069-D401-U1-A0-7618
Data Communication with the PLC
The SM 338 is not equipped with operator control components. Software
handles the complete configuration of the module. The housing does not
need to be opened, and jumpers do not ha ve to be insert ed.
Data communication with the CPU of the PLC takes place in the dual port
RAM of the module.
Figure 4-1 shows the organization of the dual port RAM.
P bus
SM 338
Parameter
area
Output area (not
used)
Input
area
Diagnosis
area
Write only
Write onlyRead only
Read only
Figure 4-1 Organization of the dual port RAM
Introduction
Data communica-
tion with the PLC
Organization of
the dual port RAM
4