6 Assi
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Parameters to the Control and the PLC Pro
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03.96
6.7 Memory configuration
6-103
Siemens AG 2000 All Rights Reserved
SINUMERIK 840D Installation and Start-Up Guide (IAD) – 04.00 Edition
!
Caution
Before increasing the DRAM areas (e.g. local user variables, function
parameters), check first that there is enough memory available (MD 18050
must be higher than 15000). If more dynamic memory is requested than is
available, the SRAM is also erased without prior warning the next time the
control is powered up and the following user data are lost:
– Drive machine data
– Part programs
– Memory configuration data
– Configurable memory areas
References: /FB/, Step7, Memory Configuration
6.7.1 Dynamic RAM memory
Set the following machine data:
Table 6-6 MDs for allocating DRAM
MDs for DRAM Meaning
MD 18242: MM_MAX_SIZE_OF_LUD_VALUE This data is preset to 8192 bytes for “Cycle 95”. It can be
reduced to 2048 if Cycle 95 is not in use.
MD 28040: MM_LUD_VALUE_MEM Memory size for local user variables.You should increase
this MD from 25 Kbytes (default) to 35 – 50 Kbytes only if
you need more than 2048 bytes in MD 18242.
Check the available DRAM memory area in MD 18050. Values of more than
15000 must be displayed. If the value is lower, the memory resources are ex-
hausted and there is a risk that user data will be lost if more DRAM memory
space is allocated.
DRAM check
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