External Control; Operating Modes Of The Drive; Speed Control Mode; Torque Control Mode - ABB ACS850 Manual

External control

When the drive is in external control, control commands are given through the
fieldbus interface (via an embedded fieldbus interface or an optional fieldbus adapter
module), the I/O terminals (digital and analogue inputs), optional I/O extension
modules or the drive-to-drive link. External references are given through the fieldbus
interface, analogue inputs, drive to drive link and encoder inputs.
Two external control locations, EXT1 and EXT2, are available. The user can select
control signals (e.g. start and stop) and control modes for both external control
locations. Depending on the user selection, either EXT1 or EXT2 is active at a time.
Selection between EXT1/EXT2 is done via digital inputs or fieldbus control word.

Operating modes of the drive

The drive can operate in several control modes.

Speed control mode

Motor rotates at a speed proportional to the speed reference given to the drive. This
mode can be used either with estimated speed used as feedback, or with an encoder
or resolver for better speed accuracy.
Speed control mode is available in both local and external control.

Torque control mode

Motor torque is proportional to the torque reference given to the drive. This mode can
be used either with or without an encoder or resolver. When used with an encoder or
resolver, this mode provides for more accurate and dynamic motor control.
Torque control mode is available in both local and external control.

Special control modes

In addition to the above-mentioned control modes, the following special control
modes are available:
• Emergency stop modes OFF1 and OFF3: Drive stops along the defined
deceleration ramp and drive modulation stops.
• Jogging mode: Drive starts and accelerates to the defined speed when the
jogging signal is activated.
For more information, see parameter group
Control locations and operating modes 55
10 Start/stop/dir on page 124.