Siemens SINUMERIK 840C Installation Instructions Manual page 1042

10.94
Loading the UMS
Now that the "Flexible memory configuration" function has been introduced, the user can
prevent loading of the UMS by setting NC-MD 60000 in file NCMEMCFG to zero.
With previous SW versions, the UMS analysis is initiated after UMS loading; this analysis
function outputs alarm 91 "ID number in UMS header incorrect" if it detects an error in the
UMS. This check function is not performed if UMS loading has been disabled (MD 60000 =
0). There are two causes of errors which may be detected in the UMS header:
• A faulty UMS has been loaded.
• The user intended to load a UMS (MD 60000 not equal to zero), but the memory reserved
for this purpose is smaller than the UMS to be loaded. In such cases, no UMS loading
takes place (zeros are set in the memory).
The alarm text "ID number in UMS header incorrect" is changed to "UMS not valid" so
that it is applicable to both these different error causes.
Restriction relating to R parameters
Channel-specific R parameters must be assigned numbers within the range used to date
[0.699] for compatibility reasons which means that there cannot be more than 700 channel-
specific R parameters. However, a smaller number of these parameters can be selected. This
restriction does not apply to central R parameters (number range used to date [700, 1299]). It
is permissible to program more than 1299 central R parameters.
However, if the selected number of R parameters is lower than the default setting (700
channel-specific and 600 central R parameters) or if the R parameter setting is set to zero, the
Siemens standard cycles cannot be processed (see Programming Guide).
With this increase in the number of central R parameters, these new R parameters can be
used in part programs (e.g. X = R3000). If the same part program is processed on another
control which has a different configuration of the R parameter memory and does not contain
this R3000 parameter, processing of the part program is interrupted and the alarm "General
programming error" output.
Block buffer
The selected number of block buffers determines the maximum number of part program blocks
which can be pre-decoded during processing. This number may have a direct effect on the
block change times. In the case of part programs with a large number of blocks and short axis
traversing paths (and high feedrate), it is meaningful to set a large number of block buffers. In
contrast, it is not meaningful to select a large number of block buffers for part programs with
long axis traversing paths (and low feedrate), particularly as timing problems relating to
"Refresh" occur when a large number of block buffers is programmed. Refresh of a block
buffer takes approximately 2 ms with the NC module with 80386 CPU 20 MHz and the
standard M configuration. The entire SSV is refreshed when single blocks are processed, i.e.
when 600 block buffers are programmed, there is a 1.2 second delay before the next single
block can be processed.
When a SINUMERIK 840C system or a SW upgrade is purchased, the number of channels for
a specific machine tool has already been decided, i.e. this is the maximum number of channels
which can be used on this machine tool. At least 21 block buffers must be reserved for each
of these channels. The Siemens configuration file NCMEMCFG works on the assumption that
all 6 channels will be activated, i.e. that 23 block buffers are assigned to each of the 6
channels. The user can set the number of block buffers for unused channels to zero and thus
gain approximately 76 KB memory for each channel.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
12.25.4 Memory configuration on control power-up
6FC5197- AA50
12 Functional Descriptions
12–267