Table 4-21 Feedback Resolution Based On Frequency And Voltage Level; Table 4-22 Encoder Output Types; Table 4-23 Buffered Encoder Connections - Emerson Digitax ST User Manual

Safety Product Mechanical
Information information installation
SC, SC.HiPEr, EndAt, SC.EndAt, SSI and SC.SSI encoders
1 Channel Cos*
2 Channel Cosref*
3 Channel Sin*
4 Channel Sinref*
Type
Maximum Signal level
Maximum input frequency
Maximum applied differential
voltage and common mode
voltage range
For the SinCos encoder to be compatible with Digitax ST, the output
signals from the encoder must be a 1V peak to peak differential voltage
(across Sin to Sinref and Cos to Cosref).
The majority of encoders have a DC offset on all signals. A number of
encoder manufactures typically have a 2.5Vdc offset. The Sinref and
Cosref are a flat DC level at 2.5Vdc and the Cos and Sin signals have a
1V peak to peak waveform biased at 2.5Vdc.
Encoders are available which have a 1V peak to peak voltage on Sin,
Sinref, Cos and Cosref. This results in a 2V peak to peak voltage seen
at the drive's encoder terminals. It is not recommended that encoders of
this type are used with Digitax ST, and that the encoder feedback
signals should meet the above parameters (1V peak to peak).
Resolution: The sinewave frequency can be up to 500kHz but the
resolution is reduced at high frequency. Table 4-21 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. Although it is possible to obtain 11 bits of interpolation
information, the nominal design value is 10 bits.
* Not used with EndAt and SSI communications only encoders.

Table 4-21 Feedback resolution based on frequency and voltage level

Volt/Freq 1kHz 5kHz
1.2 11 11
1.0 11 11
0.8 10 10
0.6 10 10
0.4 9 9
5 Data**
6 Data\**
11 Clock***
12 Clock\***
Type
Maximum frequency
Line loading
Working common mode range
Absolute maximum applied
voltage relative to 0V
Absolute maximum applied
differential voltage
** Not used with SC encoders.
*** Not used with SC and SC.HiPEr encoders.
Digitax ST User Guide
Issue: 3
Electrical Getting Basic
installation started parameters
Differential voltage
1.25V peak to peak (sin with regard
to sinref and cos with regard to
cosref)
See Table 4-21
±4V
50kHz 100kHz 200kHz
10 10 9
10 9 9
10 9 8
9 9 8
9 8 7
EIA 485 differential transceivers
2MHz
32 unit loads (for terminals 5 and 6)
1 unit load (for terminals 11 and 12)
+12V to –7V
+14V to -9V
+14V to -9V
www.controltechniques.com
Running the SMARTCARD
Optimization
motor Operation
14 0V common
15 Motor thermistor input
This terminal is connected internally to terminal 8 of the signal
connector. Connect only one of these terminals to a motor thermistor.
Analog input 3 must be in thermistor mode, Pr 7.15 = th.SC (7), th (8) or
th.diSP (9).
4.16.2 Buffered encoder output
NOTE
The buffered encoder output is sourced from the drive encoder input and
can be any incremental type or any SINCOS type (Note: - No output is
available if EndAt only or SSI communications only encoders are used).
If a SINCOS is used as the source the buffered output is derived from
the zero crossings of the sine waves and does not include interpolated
information. The buffered encoder output provides an output with
minimal delay from the drive encoder input (maximum delay is 0.5µs). If
the source encoder does not have a marker pulse, then no marker pulse
can be obtained from the buffered encoder output.

Table 4-22 Encoder output types

Setting of
Pr 3.54
Ab (0) Quadrature outputs
Fd (1) Frequency and direction outputs
Fr (2) Frequency and reverse outputs
Ab.L (3) Quadrature outputs with marker lock
Fd.L (4) Frequency and direction outputs with marker lock

Table 4-23 Buffered encoder connections

Term.
Ab
(0)
1 A
2 A\
500kHz
3 B
8 4 B\
5
7
6
7
14
7
6
*Available when marker pulse input connected
1 A, F
2 A\, F\
3 B, D, R
4 B\, D\, R\
5 Z
6 Z\
Type
Max frequency
Max load capability
Working common mode range
Absolute maximum applied
voltage relative to 0V
14 0V common
Onboard Advanced Technical
Diagnostics
PLC parameters Data
Description
Setting of Pr 3.54
Fd Fr Ab.L
(1) (2)
F F
F\ F\
D R
D\ R\
Z*
Z\*
0V
EIA 485 differential transmitter
512 KHz
31 units
+12V to -7V
+14V to -14V
UL listing
information
Fd.L
(3) (4)
A F
A\ F\
B D
B\ D\
39