Siemens SINUMERIK 840C - Manual (Page 964)

09.95 12 Functional Descriptions
12.19.4 Temperature compensation TC
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
TCabs
• Reference point P
0
for position-dependent compensation
• Coefficient tanß of position-dependent compensation
• Activation flags of the two compensation modes
The compensation value K
TC
is calculated internally from these values and the current actual
position. This compensation value is then included in the position control calculation.
The following applies to the sign:
Error K
TC
= Machine position - Setpoint
i.e. when the K
TC
is positive, the axis traverses in a negative direction.
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 DR
DW n
DW n
DW n
DW n
DW n
DW n
DW n
DW n+1
+2
+3
+4
+5
+6
+7
Axis number (1-30)
Low
Low
Low
High
High
High
Activation flags
Bit U:
Bit A:
1 - Position-independent TC operative
0 - Position-independent TC inoperative
1 - Position-dependent TC operative
0 - Position-dependent TC inoperative
U A
0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1
Length in words (word 7 in KF)
Absolute TC value K
TCabs
Coefficient tan ß
Reference point P
0
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 6FC5197- AA50 12–189
SINUMERIK 840C (IA)