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Chapter 9 Setup
9–12
If the linear motor's pole direction and linear scale's feedback direction are same, the state is called
forward polarity. If these directions differ, the state is called reverse polarity. Normally, these are
installed to achieve forward polarity, but can be installed to achieve reverse polarity. The polarity
achieved with the linear motor and linear scale installation directions is shown below. Refer to this
table, and set the pole direction and feedback direction relation in the following parameter. When this
parameter is set, the servo driver's position direction can be reversed. Thus, the position data
displayed on the CNC Servo Monitor screen will have a plus/minus direction opposite from the linear
scale feedback direction.
(The Heidenhain scale indicates the case of the A, B phase analog output of the measurement length
system LS, LIDA and LIF. Thus, when using another scale, confirm that the A and B phase analog
outputs have the same relation.
No. Abbrev.
Parameter
name
Details
SV017 SPEC Servo
specifica-tion
s
This is a HEX setting parameter. Set this as follows according to the servo specification.
Table of feedback polarities according to linear motor and linear scale installation directions
Connected scale AT342 scale Heidenhain scale
Item Polarity SPEC (fdir) Polarity SPEC (fdir)
Fig. 9.3.1 (1) Forward polarity 0 Reverse polarity 1
Fig. 9.3.1 (2) Reverse polarity 1 Forward polarity 0
Fig. 9.3.1 (3) Reverse polarity 1 Forward polarity 0
Fig. 9.3.1 (4) Forward polarity 0 Reverse polarity 1
Fig. 9.3.2 (1) Reverse polarity 1 Forward polarity 0
Fig. 9.3.2 (2) Forward polarity 0 Reverse polarity 1
Fig. 9.3.2 (3) Forward polarity 0 Reverse polarity 1
Fig.
No.
Fig. 9.3.2 (4) Reverse polarity 1 Forward polarity 0
Power line
connector
(1)
(4)
(3)
(2)
Detection head
Signal cable
Power line
connector
Detection head
Signal cable
Power line
connector
Detection head
Signal cable
Detection head
Power line
connector
Signal cable
Fig. 9.3.1 When linear scale detection head is installed on motor's primary side
(This is for the AT342. The signal cable direction is reversed for the Heidenhain
scale.)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
spm drvall drvup mpt3 mp abs vmh vdir fdir seqh dfbx vdir2
Bit Meaning when "0" is set Meaning when "1" is set
4 fdir Main side (CN2) feedback forward
polarity
Main side (CN2) feedback reverse
polarity