T-Series/Commands/Move At Constant Speed/General
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| Instruction Name | Move At Constant Speed |
|---|---|
| Applies to | All motorized devices |
| Firmware Version | 5.00 and up |
| 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 Set Acceleration (Cmd 43)) 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 Set Device Mode (Cmd 40) bit 4.
If the device reaches its end of travel, the device stops and the new position is returned via reply-only command Limit Active (Cmd 9).
This command may pre-empt, or be pre-empted by Move to Stored Position (Cmd 18), Move Absolute (Cmd 20), Move Relative (Cmd 21), Move at Constant Speed (Cmd 22) and Stop (Cmd 23).
For a spreadsheet that can be used to calculate speed setting values for any product see http://www.zaber.com/documents/ZaberSpeedSetting.xls. Alternatively you may use the formulas below.
The conversion between device speed and command data value depends on the device firmware version:
- T-Series devices - Firmware 5.xx
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
Maximum data value is 512*R-1. Note that the maximum speed possible is independent of the resolution. In Firmware 5.21 and 5.22, a value of 0 is not allowed. In all other versions, target speed of 0 will cause Move Absolute/Relative and Move to Stored Position commands to return an error.
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.
- A-Series devices - Firmware 6.xx
Actual Speed
- = Data / 1.6384 * M mm/s or deg/s
- = Data / 1.6384 microsteps/s
- = Data / 1.6384 / R steps/s
- = Data / 1.6384 / (R x S) * 60 revolutions/min Motor rpm
- = Data / 1.6384 * 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
Valid data values are from 1 to (16384*R). Note that the maximum speed possible is independent of the resolution.
Refer to product specifications for the distance corresponding to a single microstep or revolution.
For example, if a motor has 200 steps per revolution (S = 200), used with default resolution (R = 64), and Data is 153600, then the motor will move at a speed of 720 revolutions per minute.
