Functional Description; Data Structure - Siemens SINUMERIK 840C Installation Instructions Manual

09.95
12.19.4.2

Functional description

Temperature error compensation can be performed for every axis. The parameters for TC can
only be transferred via the command channel of the PLC to the NC.
The following parameters must be defined and transferred for every axis that is to be
compensated:
• A position-independent compensation value K
• Reference point P for position-dependent compensation
0
• Coefficient tanß of position-dependent compensation
• Activation flags of the two compensation modes
The compensation value K
position. This compensation value is then included in the position control calculation.
The following applies to the sign:
Error K = Machine position - Setpoint
TC
i.e. when the K is positive, the axis traverses in a negative direction.
TC
12.19.4.3

Data structure

The transfer of data from the PLC to the NC via the command channel is implemented via
function number 9 (entry in DB41).
Data must be transferred separately for each axis. These data are erased after power on which
means that the temperature compensation function is no longer effective.
The contents of the user DB are as follows for each axis:
Format of user DB:
DL
Length in words (word 7 in KF)
DW n
0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1
Axis number (1-30)
DW n+1
DW n +2
Absolute TC value K
DW n +3
DW n +4
Coefficient tan ß
DW n +5
DW n +6
Reference point P
DW n +7
Activation flags:
These flags are used to determine which TC methods are to be applied. Both methods can be
active at the same time.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
TCabs
is calculated internally from these values and the current actual
TC
DR
Activation flags
U A
High
TCabs
Low
High
Low
High
0
Low
6FC5197- AA50
12 Functional Descriptions
12.19.4 Temperature compensation TC
1 - Position-independent TC operative
Bit U:
0 - Position-independent TC inoperative
1 - Position-dependent TC operative
Bit A:
0 - Position-dependent TC inoperative
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