P
+ or −
0 to 9
0 to 9
0 to 9
0 to 9
0 to 9
CR
Upper 15 bits
of position data
Fig. 182: Data Format of PAO Signal
7.10.7 Calculating the Current Position in Machine Coordinates
With an absolute linear encoder, you must set the position of the origin (i.e., the origin of
the machine coordinate system).
The host controller reads the coordinate from the origin of the encoder coordinate
system. The host controller must record the value of this coordinate.
The method to calculate the coordinate value of the present position from the origin of the
machine coordinate system is given below.
The position data from the absolute linear encoder is signed 36-bit data, but the upper 16
bits (with sign) and the lower 20 bits are output separately.
For the upper 16-bit data (with sign), the upper bits (16 bits, including the sign) of the cur-
rent position after dividing by the setting of Pn281 are output with serial communications
according to the transmission specifications.
For the lower 20-bit data, the lower bits (20 bits) of the current position after dividing by
the setting of Pn281 are output as a pulse train.
Machine coordinate
Value of upper
16-bit data
(with sign)
0
1
2 3
Origin (reference position) Current position
MO × R
PE
PO
PS
PMPS’MS × R
Origin of absolute
linear encoder
Fig. 183: Calculating the Current Position in Machine Coordinates
The current position P
M
in the machine coordinate system is calculated as follows:
P
M
= P
E
- P
S
P
E
= M
O
× R + P
O
P
S
= M
S
× R + P
S
’
Symbol Meaning
P
E
Position data for the current position of the absolute linear encoder
M
O
Upper 16 bits (with sign) of the position data for the current position of
the absolute linear encoder
P
O
Lower 20 bits of the position data for the current position of the abso-
lute linear encoder
P
S
Position data of the origin
M
S
Upper 16 bits (with sign) of the position data of the origin
Sigma-7 Series SERVOPACKs
Application Functions
Absolute Linear Encoders > Calculating the Current Position in Machine Coordinates
| | PROFINET Communications - SIEP YEUOC7P 02A Revision 0 | en | 243
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