ABB ACS880 - Encoder Echo and Emulation; Load and Motor Feedback

• Resolver interface FEN-21: resolver input, TTL input, TTL output (for encoder
emulation and echo) and two digital inputs
• HTL encoder interface FEN-31: HTL encoder input, TTL output (for encoder
emulation and echo) and two digital inputs
• HTL/TTL encoder interface FSE-31 (for use with an FSO-xx safety functions module):
Two HTL/TTL encoder inputs (one HTL input supported at the time of publication).
The interface module is to be installed onto one of the option slots on the drive control
unit. The module (except the FSE-31) can also be installed onto an FEA-03 extension
adapter.
Encoder echo and emulation
Both encoder echo and emulation are supported by the above-mentioned FEN-xx
interfaces.
Encoder echo is available with TTL, TTL+ and HTL encoders. The signal received from
the encoder is relayed to the TTL output unchanged. This enables the connection of
one encoder to several drives.
Encoder emulation also relays the encoder signal to the output, but the signal is either
scaled, or position data converted to pulses. Emulation can be used when absolute
encoder or resolver position needs to be converted to TTL pulses, or when the signal
must be converted to a different pulse number than the original.
Load and motor feedback
Three different sources can be used as speed and position feedback: encoder 1, encoder
2, or motor position estimate. Any of these can be used for load position calculation or
motor control. The load position calculation makes it possible, for example, to determine
the position of a conveyor belt or the height of the load on a crane. The feedback sources
are selected by parameters 90.41 and 90.51.
For detailed parameter connections of the motor and load feedback functions, see the
block diagrams on pages 627 and 628. For more information on load position calculation,
see section Position counter (page 56).
Any mechanical gear ratios between the components (motor, motor encoder, load, load
encoder) are specified using the gear parameters shown in the diagram below.
Program features 55