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Examples/applications
6.8 Determing the memory requirement in the SIMATIC
6.8
Determing the memory requirement in the SIMATIC
6.8
The memory resources used in SIMATIC S7 by a MOBY application should normally not
reach the system limits on the PLC. However, if the following conditions occur
simultaneously, the memory requirement must be considered:
• SIMATIC S7 with small memory configuration
• Many MOBY channels (write/read devices) are processed in one S7.
• Processing of large volumes of data on each MOBY channel
The following example shows a configuration for the memory required by FC 45 in an S7.
Twenty write/read devices with 1KB of MDS data each are to be processed:
FC 45 (needed once)
Parameter data block (UDT 10)
Command data block (UDT 20)
DB for MDS data
Total
In this configuration, a SIMATIC CPU with only 48 KB memory can reach the memory limits
quickly if further programs are also running.
6-20
per channel
Function manual, Release 03/2006 , J31069-D0167-U001-A2-7618
Memory Requirements [KB]
Total
–
~7
0.3
6
0.01
0.2
1
20
1.31
33.2
FC 45
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