Emerson SI-Universal User Manual page 56

1x.027
Minimum
Default
Type
Display Format
Coding
Provided the set-up parameters for the position feedback device connected to the drive P1 position
interface are correct, P1 Speed Feedback (1x.027) shows the speed derived from the feedback.
The speed is given in mm/s if P1 Linear Feedback Select (1x.051) = 1 and Linear Speed Select
(1x.055) on the drive = 1, otherwise it is given in rpm. The value shown is measured over a 16 ms
sliding window period.
1x.028
Minimum
Default
Type
Display Format
Coding
P1 Revolution/Pole Pitch Counter (1x.028), P1 Position (1x.029) and P1 Fine Position (1x.030)
combined, give the encoder position with a resolution of 1/2
number. If a rotary position feedback device is being used (P1 Linear Feedback Select (1x.051) =
0), then these quantities relate directly to the rotary position of the feedback device. If a linear
feedback device is used, then one revolution or pole pitch relates to the distance given by P1 Pole
Pitch (1x.055).
47
Revolutions/Pole Pitches
Provided the position feedback interface set-up parameters are correct, the position is always
converted to units of 1/2
relevant depending on the resolution of the feedback device. For example a 1024 line digital
encoder produces 4096 counts per revolution, and so the position is represented by the bits in the
shaded area only.
47
Revolutions/Pole Pitches
When the position feedback moves by more than one revolution or pole pitch, the P1 Revolution/
Pole Pitch Counter (1x.028) increments or decrements in the form of a sixteen bit roll-over counter.
If an absolute position feedback device (except AB Servo, FD Servo, FR Servo, SC Servo) is used,
the position is initialized at power-up and each time the encoder is subsequently initialized with the
absolute position including the revolution count if a multi-turn absolute rotary encoder is used, or
the pole pitch count if an absolute linear encoder is used.
The position interface parameter descriptions cover rotary and linear applications, but the
revolutions or pole pitches are always referred to as turns.
56
P1 Speed Feedback
-214748364.8
32 Bit Volatile
None
RO, FI, ND, NC, PT
P1 Revolution/Pole Pitch Counter
0
16 Bit Volatile
None
RO, ND, NC, PT, BU
32 31
Position
32
of a revolution/pole pitch, but some parts of the value may not be
32 31
Position
Maximum
Units
Update Rate
Decimal Places
Maximum
Units
Update Rate
Decimal Places
32
of a revolution/pole pitch as a 48 bit
16 15
Fine Position
20 19 16 15
SI-Universal Encoder User Guide
214748364.7
rpm
4 ms write
1
65535
4 ms write
0
Fine Position
0
0
Issue: 2