Festo Электроцилиндр - Manual (Page 15)

2 Overview
Festo – GDCP-CMMO-ST-EA-SY-EN – 1301a – English 15
2.2.4 Closed loop versus open-loop operation
Regulated (with positional feedback), motor with encoder (closed-loop operation)
In closed-loop operation the rotor position of the motor is detected by an incremental encoder/encoder
and reported back to the controller (closed loop).
The force mode is only possible in closed-loop operation. Running or referencing to stop is also only
possible in closed-loop operation.
In closed-loop operation only the energy required to move the load is supplied to the motor, i.e. the
motor operates in an energy-optimised manner with low heat generation.
Controlled (without positional feedback), motor with/without encoder (open-loop operation)
In open-loop operation (without feedback of the rotor position) only the positioning mode and speed
mode, as well as homing to proximity sensor or to “current position” are possible.
When travelling to a stop it can result in step losses and thus to defective position values.
In open-loop operation the motor is always operated with the set driving current when travelling and
with the set holding current when at a standstill.
Operation of motors with an encoder can also be parameterised so that no feedback from the encoder
is required.
2.3 Overview of CMMO-ST operating modes
Records
Orders are stored in a record table in CMMO-ST in the form of parameter records. Each record contains
all of the information required for a specific function depending on the selected mode.
During operation, the higher-order controller (PLC) then makes a successive selection from the records
that are saved in the CMMO-ST (“record selection”).
2.3.1 Positioning mode
During positioning mode the positioning tasks are saved as a “position record” in the record table.
Each position record includes information about the target position, speed, acceleration, etc.
In the binary profile record linking can also be configured.
2.3.2 Speed mode
The drive moves at a specified speed. The corresponding records in the record table are designated
speed records. There are speed records with and without stroke limit.
The speed mode is only available in the binary profile.
2.3.3 Force mode
The motor generates a predetermined torque. Depending on the mechanics this results in a torque or
linear force. The corresponding records in the record table are designated force records. There are
force records with and without stroke limit.
The force mode is only possible with closed-loop operation (motor with encoder) and is only available
in the binary profile.