Activate Default Memory - Only 840D Sl; Read And Write Plc Variable - Only 840D Sl - Siemens SINUMERIK 840D sl Function Manual

MD28530 $MC_MM_PATH_VELO_SEGMENTS > 1 (number of memory elements for limiting
the path velocity)
A setting of 5 is recommended. This setting need not be made if only involute sections are
used which have radii of curvature that change over a relatively small area.
2.3.3

Activate DEFAULT memory - only 840D sl

GUD start values
The DEF... / REDEF... NC commands can be used to assign default settings to global user
data (GUD). To make these default values available at the parameterized initialization time,
e.g. with the attribute INIPO, after power on, they must be saved permanently in the system.
The required memory space must be enabled using the following machine data:
MD18150 $MM_GUD_VALUES_MEM (non-volatile memory space for GUD values)
References:
Function Manual, Extended Functions; S7: "Memory Configuration"
Programming Manual, Job Planning
2.3.4

Read and write PLC variable - only 840D sl

High-speed data channel
For high-speed exchange of information between the PLC and NC, a memory area is reserved
in the communications buffer on these modules (dual-port RAM). Variables of any type (I/O,
DB, DW, flags) may be exchanged within this memory area.
The PLC accesses this memory using 'Function Calls' (FC) while the NC uses system variables.
Organization of memory area
The user's programming engineer (NC and PLC) is responsible for organizing (structuring) this
memory area.
Every storage position in the memory can be addressed provided that the limit is selected
according to the appropriate data format (i.e. a DWORD for a 4-byte limit, a WORD for a 2-
byte limit, etc.).
The memory is accessed via the data type and the position offset within the memory area.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
A2: Various NC/PLC interface signals and functions
2.3 Functions
57