Control Techniques Digitax ST Advanced User's Manual page 52

Parameter
Menu 3
structure
Drive encoder speed feedback
3.27
Bit SP
Coding
Range ±40,000.0 rpm
Update rate 4ms write
Provided the set-up parameters for the drive encoder are correct this parameter shows the encoder speed in rpm.
It should be noted that the value shown by this parameter is measured over a 16ms sliding window period (in the same way as Pr 3.02), and so the
ripple in this parameter accessible via comms or by a Solutions Module is as defined for Pr 3.02. The FI attribute for this parameter is set, and so
further filtering is applied when this parameter is viewed with one of the drive keypads.
Drive encoder revolution counter
3.28
Bit SP
Coding
Range 0 to 65,535 revolutions
Update rate 4ms write
Drive encoder position
3.29
Bit SP
Coding
Range
0 to 65,535 (1/2
Update rate 4ms write
Drive encoder fine position
3.30
Bit SP
Coding
Range
0 to 65,535 (1/2
Update rate 4ms write
These parameters effectively give the encoder position with a resolution of 1/2
47 32 31
Revolutions Position
Provided the encoder set-up parameters are correct, the position is always converted to units of 1/2
may not be 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 32 31
Revolutions Position
When the encoder rotates by more than one revolution, the revolutions in Pr 3.28 increment or decrement in the form of a sixteen bit roll-over counter.
If an absolute position feedback device (except an encoder with commutation signals) is used the position is initialized at power-up with the absolute
position. If a multi-turn absolute encoder is used the revolution counter is also initialized with the absolute revolutions at power-up.
If a linear encoder is used the turns information is used to represent movement by the number of poles defined by Pr 5.11 (or 21.11 for motor map 2).
Therefore if the number of poles is set to two, one revolution is the movement by one pole pitch.
Drive encoder marker position reset disable
3.31
Bit SP
Coding
1
Default 0
Update rate Background read
Drive encoder marker flag
3.32
Bit SP
Coding
1
Default 0
Update rate 250μs write
52
Keypad and
Parameter x.00
display
FI DE Txt VM DP ND
1 1 1
FI DE Txt VM DP ND
1 1
FI DE Txt VM DP ND
1 1
16
ths of a revolution)
FI DE Txt VM DP ND
1 1
32
ths of a revolution)
16 15
Fine position
20 19 16 15
Fine position
FI DE Txt VM DP ND
FI DE Txt VM DP ND
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Parameter Advanced parameter
description format descriptions
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
32
ths of a revolution as a 48 bit number as shown below.
0
0
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
Serial comms Electronic
protocol nameplate
PS
PS
1
PS
1
PS
1
32
ths of a revolution, but some parts of the value
PS
PS
Digitax ST Advanced User Guide
Issue Number: 1
Performance