This is the description of the Modbus protocol for the Silent Stepper Brick. General information and technical specifications for the Silent Stepper Brick are summarized in its hardware description.
A general description of the Modbus protocol structure can be found here.
Function ID: | 1 |
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Request: |
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Response: | no response |
Sets the maximum velocity of the stepper motor in steps per second. This function does not start the motor, it merely sets the maximum velocity the stepper motor is accelerated to. To get the motor running use either set_target_position, set_steps, drive_forward or drive_backward.
Function ID: | 2 |
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Request: | empty payload |
Response: |
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Returns the velocity as set by set_max_velocity.
Function ID: | 3 |
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Request: | empty payload |
Response: |
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Returns the current velocity of the stepper motor in steps per second.
Function ID: | 4 |
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Request: |
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Response: | no response |
Sets the acceleration and deacceleration of the stepper motor. The values are given in steps/s². An acceleration of 1000 means, that every second the velocity is increased by 1000 steps/s.
For example: If the current velocity is 0 and you want to accelerate to a velocity of 8000 steps/s in 10 seconds, you should set an acceleration of 800 steps/s².
An acceleration/deacceleration of 0 means instantaneous acceleration/deacceleration (not recommended)
The default value is 1000 for both
Function ID: | 5 |
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Request: | empty payload |
Response: |
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Returns the acceleration and deacceleration as set by set_speed_ramping.
Function ID: | 6 |
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Request: | empty payload |
Response: | no response |
Executes an active full brake.
Warning
This function is for emergency purposes, where an immediate brake is necessary. Depending on the current velocity and the strength of the motor, a full brake can be quite violent.
Call stop if you just want to stop the motor.
Function ID: | 11 |
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Request: |
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Response: | no response |
Sets the number of steps the stepper motor should run. Positive values will drive the motor forward and negative values backward. The velocity, acceleration and deacceleration as set by set_max_velocity and set_speed_ramping will be used.
Function ID: | 12 |
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Request: | empty payload |
Response: |
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Returns the last steps as set by set_steps.
Function ID: | 13 |
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Request: | empty payload |
Response: |
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Returns the remaining steps of the last call of set_steps. For example, if set_steps is called with 2000 and get_remaining_steps is called after the motor has run for 500 steps, it will return 1500.
Function ID: | 16 |
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Request: | empty payload |
Response: | no response |
Drives the stepper motor forward until drive_backward or stop is called. The velocity, acceleration and deacceleration as set by set_max_velocity and set_speed_ramping will be used.
Function ID: | 17 |
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Request: | empty payload |
Response: | no response |
Drives the stepper motor backward until drive_forward or stop is triggered. The velocity, acceleration and deacceleration as set by set_max_velocity and set_speed_ramping will be used.
Function ID: | 18 |
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Request: | empty payload |
Response: | no response |
Stops the stepper motor with the deacceleration as set by set_speed_ramping.
Function ID: | 22 |
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Request: |
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Response: | no response |
Sets the current in mA with which the motor will be driven. The minimum value is 360mA, the maximum value 1640mA and the default value is 800mA.
Warning
Do not set this value above the specifications of your stepper motor. Otherwise it may damage your motor.
Function ID: | 23 |
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Request: | empty payload |
Response: |
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Returns the current as set by set_motor_current.
Function ID: | 24 |
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Request: | empty payload |
Response: | no response |
Enables the driver chip. The driver parameters can be configured (maximum velocity, acceleration, etc) before it is enabled.
Function ID: | 25 |
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Request: | empty payload |
Response: | no response |
Disables the driver chip. The configurations are kept (maximum velocity, acceleration, etc) but the motor is not driven until it is enabled again.
Function ID: | 26 |
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Request: | empty payload |
Response: |
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Returns true if the driver chip is enabled, false otherwise.
Function ID: | 27 |
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Request: |
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Response: | no response |
Sets the basic configuration parameters for the different modes (Stealth, Coolstep, Classic).
If you want to use all three thresholds make sure that Stealth Threshold < Coolstep Threshold < Classic Threshold.
The default values are:
Function ID: | 28 |
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Request: | empty payload |
Response: |
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Returns the configuration as set by set_basic_configuration.
Function ID: | 7 |
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Request: |
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Response: | no response |
Sets the current steps of the internal step counter. This can be used to set the current position to 0 when some kind of starting position is reached (e.g. when a CNC machine reaches a corner).
Function ID: | 8 |
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Request: | empty payload |
Response: |
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Returns the current position of the stepper motor in steps. On startup the position is 0. The steps are counted with all possible driving functions (set_target_position, set_steps, drive_forward or drive_backward). It also is possible to reset the steps to 0 or set them to any other desired value with set_current_position.
Function ID: | 9 |
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Request: |
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Response: | no response |
Sets the target position of the stepper motor in steps. For example, if the current position of the motor is 500 and set_target_position is called with 1000, the stepper motor will drive 500 steps forward. It will use the velocity, acceleration and deacceleration as set by set_max_velocity and set_speed_ramping.
A call of set_target_position with the parameter x is equivalent to a call of set_steps with the parameter (x - get_current_position).
Function ID: | 10 |
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Request: | empty payload |
Response: |
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Returns the last target position as set by set_target_position.
Function ID: | 14 |
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Request: |
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Response: | no response |
Sets the step resolution from full-step up to 1/256-step.
If interpolation is turned on, the Silent Stepper Brick will always interpolate your step inputs as 1/256-step. If you use full-step mode with interpolation, each step will generate 256 1/256 steps.
For maximum torque use full-step without interpolation. For maximum resolution use 1/256-step. Turn interpolation on to make the Stepper driving less noisy.
If you often change the speed with high acceleration you should turn the interpolation off.
The default is 1/256-step with interpolation on.
The following meanings are defined for the parameters of this function:
Function ID: | 15 |
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Request: | empty payload |
Response: |
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Returns the step mode as set by set_step_configuration.
The following meanings are defined for the parameters of this function:
Function ID: | 19 |
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Request: | empty payload |
Response: |
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Returns the stack input voltage in mV. The stack input voltage is the voltage that is supplied via the stack, i.e. it is given by a Step-Down or Step-Up Power Supply.
Function ID: | 20 |
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Request: | empty payload |
Response: |
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Returns the external input voltage in mV. The external input voltage is given via the black power input connector on the Silent Stepper Brick.
If there is an external input voltage and a stack input voltage, the motor will be driven by the external input voltage. If there is only a stack voltage present, the motor will be driven by this voltage.
Warning
This means, if you have a high stack voltage and a low external voltage, the motor will be driven with the low external voltage. If you then remove the external connection, it will immediately be driven by the high stack voltage
Function ID: | 29 |
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Request: |
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Response: | no response |
Note: If you don't know what any of this means you can very likely keep all of the values as default!
Sets the Spreadcycle configuration parameters. Spreadcycle is a chopper algorithm which actively controls the motor current flow. More information can be found in the TMC2130 datasheet on page 47 (7 spreadCycle and Classic Chopper).
Slow Decay Duration: Controls duration of off time setting of slow decay phase. The value range is 0-15. 0 = driver disabled, all bridges off. Use 1 only with Comparator Blank time >= 2.
Enable Random Slow Decay: Set to false to fix chopper off time as set by Slow Decay Duration. If you set it to true, Decay Duration is randomly modulated.
Fast Decay Duration: Sets the fast decay duration. The value range is 0-15. This parameters is only used if the Chopper Mode is set to Fast Decay.
Hysteresis Start Value: Sets the hysteresis start value. The value range is 0-7. This parameter is only used if the Chopper Mode is set to Spread Cycle.
Hysteresis End Value: Sets the hysteresis end value. The value range is -3 to 12. This parameter is only used if the Chopper Mode is set to Spread Cycle.
Sine Wave Offset: Sets the sine wave offset. The value range is -3 to 12. This parameters is only used if the Chopper Mode is set to Fast Decay. 1/512 of the value becomes added to the absolute value of the sine wave.
Chopper Mode: 0 = Spread Cycle, 1 = Fast Decay.
Comparator Blank Time: Sets the blank time of the comparator. Available values are
A value of 1 or 2 is recommended for most applications.
Fast Decay Without Comparator: If set to true the current comparator usage for termination of the fast decay cycle is disabled.
The default values are:
The following meanings are defined for the parameters of this function:
Function ID: | 30 |
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Request: | empty payload |
Response: |
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Returns the configuration as set by set_basic_configuration.
The following meanings are defined for the parameters of this function:
Function ID: | 31 |
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Request: |
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Response: | no response |
Note: If you don't know what any of this means you can very likely keep all of the values as default!
Sets the configuration relevant for Stealth mode.
The default values are:
The following meanings are defined for the parameters of this function:
Function ID: | 32 |
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Request: | empty payload |
Response: |
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Returns the configuration as set by set_stealth_configuration.
The following meanings are defined for the parameters of this function:
Function ID: | 33 |
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Request: |
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Response: | no response |
Note: If you don't know what any of this means you can very likely keep all of the values as default!
Sets the configuration relevant for Coolstep.
The default values are:
The following meanings are defined for the parameters of this function:
Function ID: | 34 |
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Request: | empty payload |
Response: |
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Returns the configuration as set by set_coolstep_configuration.
The following meanings are defined for the parameters of this function:
Function ID: | 35 |
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Request: |
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Response: | no response |
Note: If you don't know what any of this means you can very likely keep all of the values as default!
Sets miscellaneous configuration parameters.
The default values are:
Function ID: | 36 |
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Request: | empty payload |
Response: |
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Returns the configuration as set by set_misc_configuration.
Function ID: | 37 |
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Request: | empty payload |
Response: |
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Returns the current driver status.
The following meanings are defined for the parameters of this function:
Function ID: | 42 |
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Request: |
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Response: | no response |
Sets the time base of the velocity and the acceleration of the Silent Stepper Brick (in seconds).
For example, if you want to make one step every 1.5 seconds, you can set the time base to 15 and the velocity to 10. Now the velocity is 10steps/15s = 1steps/1.5s.
The default value is 1.
Function ID: | 43 |
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Request: | empty payload |
Response: |
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Returns the time base as set by set_time_base.
Function ID: | 44 |
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Request: | empty payload |
Response: |
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Returns the following parameters: The current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.
The current consumption is calculated by multiplying the Actual Motor Current value (see set_basic_configuration) with the Motor Run Current (see get_driver_status). This is an internal calculation of the driver, not an independent external measurement.
The current consumption calculation was broken up to firmware 2.0.1, it is fixed since firmware 2.0.2.
There is also a callback for this function, see CALLBACK_ALL_DATA callback.
Function ID: | 231 |
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Request: |
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Response: | no response |
The SPITF protocol can be used with a dynamic baudrate. If the dynamic baudrate is enabled, the Brick will try to adapt the baudrate for the communication between Bricks and Bricklets according to the amount of data that is transferred.
The baudrate will be increased exponentially if lots of data is send/received and decreased linearly if little data is send/received.
This lowers the baudrate in applications where little data is transferred (e.g. a weather station) and increases the robustness. If there is lots of data to transfer (e.g. Thermal Imaging Bricklet) it automatically increases the baudrate as needed.
In cases where some data has to transferred as fast as possible every few seconds (e.g. RS485 Bricklet with a high baudrate but small payload) you may want to turn the dynamic baudrate off to get the highest possible performance.
The maximum value of the baudrate can be set per port with the function set_spitfp_baudrate. If the dynamic baudrate is disabled, the baudrate as set by set_spitfp_baudrate will be used statically.
The minimum dynamic baudrate has a value range of 400000 to 2000000 baud.
By default dynamic baudrate is enabled and the minimum dynamic baudrate is 400000.
New in version 2.0.4 (Firmware).
Function ID: | 232 |
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Request: | empty payload |
Response: |
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Returns the baudrate config, see set_spitfp_baudrate_config.
New in version 2.0.4 (Firmware).
Function ID: | 233 |
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Request: |
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Response: |
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Returns the timeout count for the different communication methods.
The methods 0-2 are available for all Bricks, 3-7 only for Master Bricks.
This function is mostly used for debugging during development, in normal operation the counters should nearly always stay at 0.
The following meanings are defined for the parameters of this function:
Function ID: | 234 |
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Request: |
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Response: | no response |
Sets the baudrate for a specific Bricklet port ('a' - 'd'). The baudrate can be in the range 400000 to 2000000.
If you want to increase the throughput of Bricklets you can increase the baudrate. If you get a high error count because of high interference (see get_spitfp_error_count) you can decrease the baudrate.
If the dynamic baudrate feature is enabled, the baudrate set by this function corresponds to the maximum baudrate (see set_spitfp_baudrate_config).
Regulatory testing is done with the default baudrate. If CE compatibility or similar is necessary in you applications we recommend to not change the baudrate.
The default baudrate for all ports is 1400000.
Function ID: | 235 |
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Request: |
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Response: |
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Returns the baudrate for a given Bricklet port, see set_spitfp_baudrate.
Function ID: | 237 |
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Request: |
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Response: |
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Returns the error count for the communication between Brick and Bricklet.
The errors are divided into
The errors counts are for errors that occur on the Brick side. All Bricklets have a similar function that returns the errors on the Bricklet side.
Function ID: | 238 |
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Request: | empty payload |
Response: | no response |
Enables the status LED.
The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.
The default state is enabled.
Function ID: | 239 |
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Request: | empty payload |
Response: | no response |
Disables the status LED.
The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.
The default state is enabled.
Function ID: | 240 |
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Request: | empty payload |
Response: |
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Returns true if the status LED is enabled, false otherwise.
Function ID: | 241 |
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Request: |
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Response: |
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Returns the firmware and protocol version and the name of the Bricklet for a given port.
This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet plugins.
Function ID: | 242 |
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Request: | empty payload |
Response: |
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Returns the temperature in °C/10 as measured inside the microcontroller. The value returned is not the ambient temperature!
The temperature is only proportional to the real temperature and it has an accuracy of +-15%. Practically it is only useful as an indicator for temperature changes.
Function ID: | 243 |
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Request: | empty payload |
Response: | no response |
Calling this function will reset the Brick. Calling this function on a Brick inside of a stack will reset the whole stack.
After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!
Function ID: | 255 |
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Request: | empty payload |
Response: |
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Returns the UID, the UID where the Brick is connected to, the position, the hardware and firmware version as well as the device identifier.
The position can be '0'-'8' (stack position).
The device identifier numbers can be found here.
Function ID: | 38 |
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Request: |
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Response: | no response |
Sets the minimum voltage in mV, below which the CALLBACK_UNDER_VOLTAGE callback is triggered. The minimum possible value that works with the Silent Stepper Brick is 8V. You can use this function to detect the discharge of a battery that is used to drive the stepper motor. If you have a fixed power supply, you likely do not need this functionality.
The default value is 8V.
Function ID: | 39 |
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Request: | empty payload |
Response: |
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Returns the minimum voltage as set by set_minimum_voltage.
Function ID: | 45 |
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Request: |
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Response: | no response |
Sets the period in ms with which the CALLBACK_ALL_DATA callback is triggered periodically. A value of 0 turns the callback off.
Function ID: | 46 |
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Request: | empty payload |
Response: |
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Returns the period as set by set_all_data_period.
Function ID: | 40 |
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Response: |
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This callback is triggered when the input voltage drops below the value set by set_minimum_voltage. The response value is the current voltage given in mV.
Function ID: | 41 |
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Response: |
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This callback is triggered when a position set by set_steps or set_target_position is reached.
Note
Since we can't get any feedback from the stepper motor, this only works if the acceleration (see set_speed_ramping) is set smaller or equal to the maximum acceleration of the motor. Otherwise the motor will lag behind the control value and the callback will be triggered too early.
Function ID: | 47 |
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Response: |
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This callback is triggered periodically with the period that is set by set_all_data_period. The response values are: the current velocity, the current position, the remaining steps, the stack voltage, the external voltage and the current consumption of the stepper motor.
Function ID: | 48 |
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Response: |
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This callback is triggered whenever the Silent Stepper Brick enters a new state. It returns the new state as well as the previous state.
The following meanings are defined for the parameters of this function: