T-Series/Commands/Move At Constant Speed/T-Series Motorized Devices

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Instruction Name Move At Constant Speed
Applies to T-Series motorized devices
Firmware Version 5.xx
Command Number 22
Command Type Command
Command Data Speed
Reply Data Speed
Safe to retry? Yes
Returns Current Position? No
Persistence n/a
Summary Moves the device at a constant speed based on the value specified in the Command Data.

This instruction specifies a direction and a speed to move, rather than a target position. When this instruction is issued the device will accelerate (at a rate determined by command #43 Set Acceleration) to the speed specified by the instruction data. The device will continue moving at this speed until a limit is reached or a pre-empting instruction is issued. Negative speeds cause retraction while positive speeds cause extension. Unlike the other movement commands, this command sends a response immediately without waiting for the move to finish.

The device may be set to return its position continuously during the move using the set mode command (#40)] bit 4. Position tracking is a reply-only command #8. If the device runs into zero position or maximum range, the device stops and the new position is returned via reply-only command #9.

This command may pre-empt, or be pre-empted by commands 18, 20, 21, 22 and 23.

For a spreadsheet that can be used to calculate speed setting values for any product see https://www.zaber.com/documents/ZaberSpeedSetting.xls. Alternatively you may use the formulas below.

Actual Speed

= Data * 9.375 * M mm/s or deg/s
= Data * 9.375 microsteps/s
= Data * 9.375 / R steps/s
= Data * 9.375 / (R x S) * 60 revolutions/min Motor rpm
= Data * 9.375 * L / (R x S) mm/s Linear devices only

where:

  • Data is the value of the command data
  • R (microsteps/step) is the microstep resolution (command 37)
  • S (steps/revolution) is the number of steps per motor revolution
  • M (mm or deg) is the microstep size
  • L (mm or deg) is the distance of linear motion per motor revolution

Refer to product specifications for the distance corresponding to a single microstep or revolution.

For example, if a motor has 48 steps per revolution (S = 48), used with default resolution (R = 64), and Data is 2922, then the motor will move at a speed of approximately 535 revolutions per minute.


Valid data values are from (−512×R−1) to (512×R−1). Note that a value of zero will cause the device to decelerate to a stop and then send Limit Active (Cmd 9).