Encoder Turns; Equivalent Lines Per Revolution - Control Techniques unidrive sp Advanced User's Manual

Menus 15 to 17 Parameter Keypad and
SM-Uni Enc Pl structure display
The marker flag is set each time the marker input becomes active, but it is not reset by the drive, and so this must be done by the user. The marker
function only operates when Ab, Fd, Fr, Ab.Servo, Fd.Servo, Fr.Servo type encoders are selected with Pr x.15.
x.09

Encoder turns

Drive modes Open-loop, Closed-loop vector, Servo, Regen
Bit SP
Coding
Open-loop, Closed-loop vector, Servo,
Range
Regen
Open-loop, Closed-loop vector, Servo,
Default
Regen
Update rate Background read
When an encoder without comms is used it is sometimes desirable to mask off the most significant bits of the revolution counter. Normally this would
be required with an absolute multi-turn encoder where the number of turns measured is less than 65,536. If Pr x.09 is zero the revolution counter (Pr
x.04) is held at zero. If Pr x.09 has any other value it defines the maximum number of the revolution counter before it is reset to zero. For example, if
Pr x.09 = 5, then Pr x.04 counts up to 31 before being reset.
When an encoder with comms is used, Pr x.09 must contain the number of bits in the comms message used to give the multi-turn information. For a
single turn comms encoder, Pr x.09 must be set to zero. It is possible for the drive to set up this parameter automatically from information obtained
from the encoder via HIPERFACE or EnDat interfaces (see Pr x.18 on page 234).
x.10

Equivalent lines per revolution

Drive modes Open-loop, Closed-loop vector, Servo, Regen
Bit SP
Coding
Open-loop, Closed-loop vector, Servo,
Range
Regen
Open-loop, Closed-loop vector, Servo,
Default
Regen
Update rate Background read
When Ab, Fd, Fr, Ab.Servo, Fd.Servo, Fr.Servo or SINCOS signals are used the equivalent number of encoder lines per revolution must be set-up
correctly in Pr x.10 to give the correct speed and position feedback. This is particularly important if the encoder is selected for speed feedback with Pr
3.26. The equivalent number of encoder lines per revolution (ELPR) is defined as follows:
Position feedback device
Ab, Ab.Servo
Fd, Fr, Fd.Servo, Fr.Servo
SC.Hiper, SC.EnDat, SC
For Ab, Fd, Fr, Ab.Servo, Fd.Servo and Fr.Servo encoders the incremental (A/B) signal frequency should not exceed 500kHz.
For SC.Hiper, SC.EnDat, SC and SC.SSI encoders the sine wave signal frequency can be up to 166kHz, but the resolution is reduced at higher
frequencies. The table below shows the number of bits of interpolated information at different frequencies and with different voltage levels at the drive
encoder port. The total resolution in bits per revolution is the ELPR plus the number of bits of interpolated information.
Volt/Freq 1,000
1.2 11
1.0 11
0.8 10
0.6 10
0.4 9
Where encoder comms alone is used as position feedback, the equivalent lines per revolution (Pr x.10) is not used in setting up the encoder interface.
It is possible for the drive to set up this parameter automatically from information obtained from the encoder via HIPERFACE or EnDat interfaces (see
Pr x.18 on page 234).
230
Parameter Parameter
x.00 description format
FI DE Txt VM DP ND
2
2
FI DE Txt VM DP ND
0 to 50,000
4,096
ELPR
number of lines per revolution
number of lines per revolution / 2
number of sine waves per revolution
5,000 50,000 100,000
11 11 10
11 10 10
10 10 10
10 10 9
9 9 9
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Advanced parameter
Macros
descriptions
RA NC NV PT US RW BU
1 1
x
0 ≤ x ≤ 16
16
(65,536)
RA NC NV PT US RW BU
1 1
150,000
10
9
9
9
8
Serial comms Electronic
Performance
protocol nameplate
PS
1
PS
1
Unidrive SP Advanced User Guide
Issue Number: 7
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