Nord Drivesystems SK 530P - Colour and Contact Assignments for Encoders

2 Assembly and installation
BU 0600 en-2319 51
2.6 Colour and contact assignments for encoders
Encoder input
The incremental encoder connection is an input for a type with two tracks and TTL-compatible signals
for EIA RS 422-compliant drivers. The maximum current consumption of the incremental encoder
must not exceed 150 mA.
The pulse number per rotation can be between 16 and 8192 increments. This is set with the normal
scaling via parameter P301 "Incremental encoder pulse number" in the menu group "Control
parameters". For cable lengths > 20 m and motor speeds above 1500 min-1 the encoder should not
have more than 2048 pulses/revolution.
For longer cable lengths the cable cross-section must be selected large enough so that the voltage
drop in the cable is not too great. This particularly affects the supply cable, in which the cross-section
can be increased by connecting several conductors in parallel.
Unlike incremental encoders, for sine encoders or SIN/COS encoders the signals are not in the form
of pulses, but rather in the form of sine signals (shifted by 90°).
Information
Encoder signal faults
Wires that are not required (e.g. Track A inverse / B inverse) must be insulated. Otherwise, if these
wires come into contact with each other or the cable shield, short-circuits can occur that can cause
encoder signal problems or destruction of the encoder.
Information
Rotary encoder function test
The voltage difference between tracks A and B can be measured with the aid of parameter P709 [-09]
and [-10]. If the incremental encoder is rotated, the value of both tracks must jump between -0.8 V
and 0.8 V. If the voltage only jumps between 0 and 0.8 V the relevant track is faulty. The position can
no longer be reliably determined via the incremental encoder. We recommend replacement of the
encoder!
Information
Rotation direction
The counting direction of the incremental encoder must correspond to the direction of rotation of the
motor. If the two directions are not identical, the connections of the encoder tracks (Track A and Track
B) must be switched. Alternatively, the resolution (pulse number) of the encoder in P301 can be set
with a negative prefix.
Alternatively, the motor phase sequence can be changed via parameter P583
. In this way the
direction of rotation can be changed using the software only.
Incremental encoder
According to the resolution (pulse number), incremental encoders generate a defined number of
pulses for each rotation of the encoder shaft (Track A / Track A inverse) With this, the precise speed
of the encoder or motor can be measured by the frequency inverter. By the use of a second track (B /
B inverse) shifted by 90° (¼ period), the direction of rotation can also be determined.
The supply voltage for the encoder is 10 … 30 V. An external source or the internal voltage can be
used as the voltage source.
Special terminals are available for connection of a rotary encoder with TTL signals. Parameterisation
of the corresponding functions is made with the parameters from the group "Control parameters"