STEP MOTOR
CONTROLS

The key factors are motor phase current, supply voltage, desired control method, encoder connection, and installation conditions. The BAC 50 offers an adjustable phase current of up to 3 A, while the BAC 100 offers up to 10 A. Depending on the model, both support digital I/O or clock/direction control. The MiniPAC 4.0 offers up to 10 A RMS and is suitable for applications with Industrial Ethernet or SSI absolute encoders. All three models control one stepper motor axis each.

The models differ primarily in terms of motor current, supply voltage, interfaces, and connections. The BAC 50 and BAC 100 offer digital I/O or clock/direction control, as well as optional RS485. The BAC 50 operates with up to 3 A phase current and a 24–48 VDC motor supply, while the BAC 100 operates with up to 10 A and 24–60 VDC. The MiniPAC 4.0 offers up to 10 A RMS at 24–48 VDC as well as PROFINET, EtherCAT, or EtherNet/IP, and supports incremental and SSI absolute encoders.

Depending on the model, the BAC 50 and BAC 100 can be connected to a PLC via digital inputs and outputs or clock/direction signals. With digital block selection, the PLC selects a stored motion command and starts it via the START input. The MiniPAC 4.0 enables connection via PROFINET, EtherCAT, or EtherNet/IP. Included libraries and function blocks simplify its PLC integration.

The BAC 50, BAC 100, and MiniPAC 4.0 can be configured on a PC using Colibri Studio. Motion parameters, positions, and motion sequences can be set, and diagnostic functions and test runs can be utilized. The connection is established via the respective device interface; for BAC devices, a suitable interface converter is used if necessary. For the MiniPAC, the PC connection is established via Ethernet TCP/IP or USB, depending on the interface variant.

A stepper motor controller regulates the current supply to the motor phases and thus controls the movement of a stepper motor. Our devices combine a power amplifier and a positioning controller in a single compact unit. Depending on the model and operating mode, they process external motion specifications or execute stored motion commands.

The BAC 50 requires 24–36 VDC for the logic and 24–48 VDC for the motor. For the BAC 100, the logic supply is also 24–36 VDC, and the motor supply is 24–60 VDC. The MiniPAC 4.0 uses a separate 24 VDC logic supply and a 24–48 VDC motor supply.

Yes. The phase current is adjustable up to 3 A for the BAC 50, up to 10 A for the BAC 100, and up to 10 A RMS for the MiniPAC 4.0. The BAC 50 and BAC 100 also offer adjustable current reduction during standstill. The settings must be appropriate for the connected motor, the application, and the thermal installation conditions.

Yes. In the digital I/O version, up to 31 motion profiles can be stored for block selection. These can be selected via five binary-coded inputs and executed by pressing START. Alternatively, a stored program sequence can be run in block sequence mode.

In block selection, the PLC selects a stored motion command via binary-coded inputs and starts it by pressing START. The positions can be selected in any order. In "Block Execution," the programmed commands are executed in the specified order. Depending on the motion program, a new START signal triggers the next command, or appropriately configured commands continue automatically.

In the standard configuration, START is held HIGH throughout the entire motion. If START is withdrawn prematurely, the drive stops and the motion command is not fully executed. Edge detection can change this behavior depending on the parameter settings. For PLC control, therefore, the configured START evaluation is decisive.

The digital outputs “Ready” and “Motor Stopped” inform the PLC about the operating and motion status. “Motor Stopped” is HIGH when the motor is at a standstill. In an application requiring a reference run, “Ready” remains LOW until the reference run is successfully completed. During subsequent positioning, “Ready” must remain HIGH throughout the entire movement. Only the completed motion command, together with an error-free execution, confirms successful positioning; “Motor Stopped” alone does not mean that the target position has been reached.

When rotational monitoring via encoder is active, a detected blockage or step error causes the drive to stop. The “Ready” output goes LOW, signaling to the PLC that the positioning was not successfully completed. In the described block selection mode, the error is acknowledged by canceling the START command. After a successful reference run, “Ready” returns to HIGH, and a new positioning operation is possible. The position detected by the encoder is retained as long as power is on.

The higher-level controller specifies the motion via clock pulses and a direction signal. The BAC 50 and BAC 100 process these signals directly in the corresponding configuration. In this operating mode, full step, half step, quarter step, and eighth step are adjustable.

In addition to block selection and block execution, the BAC controllers in the digital I/O version support reference runs, print mark positioning, and analog speed and position setpoints. In print mark positioning, a sensor signal influences the positioning sequence. Speed or position can be specified via an external analog signal.

The BAC 50 and BAC 100 provide a connection for 5-V incremental encoders with differential A/A and B/B signals. The MiniPAC 4.0 supports incremental encoders via RS422 and absolute encoders via SSI. The encoder must be compatible with the electrical interface and pinout of the respective device.

The STO (Safe Torque Off) safety function is available as an option for the MiniPAC 4.0. Connection, function, and integration are described in the accompanying documentation.

The controllers must be installed according to their installation instructions. For the BAC 50 and BAC 100, a suitable mounting surface for heat dissipation is required; heat-insulating mounting is not permitted. The device-specific installation and cooling instructions must also be followed for the MiniPAC 4.0.