Communications protocol
A simple text-based protocol is used. Commands are sent to the SMD4, checked and executed, and a response returned. Data are buffered on receipt and commands are evaluated and executed on a first in first out basis. Although not a requirement, it is usually easiest to send a command and evaluate the response before sending the next command.
Commands are in the form (Note that angle brackets are shown for clarity only, they are not part of the protocol):
<address prefix><mnemonic>,<argument 1>,<argument 2>,<argument n>…<CR><LF>
And responses are in the form:
<address prefix>,<SFLAGS>,<EFLAGS>,<data 1>,<data 2>,<data n>…<CR><LF>
If the command executed successfully, or:
<address prefix>,<SFLAGS>,<EFLAGS>,<error code><CR><LF>
If the command failed to execute correctly.
Where:
|
Item |
Description |
|
<address prefix> |
Optional prefix included when multiple SMD4s exist on the same bus, see stuff. If not using addressing can be omitted. |
|
<mnemonic> |
Short sequence of characters representing a command, case insensitive |
|
<argument n> |
Zero or more command arguments |
|
<data n> |
Zero or more response data items |
|
<error code> |
An error code, see section Error Codes. This includes both a number and text description of the error to aid when using the SMD4 via a terminal program. |
|
<SFLAGS> |
Set of flags representing the status of the SMD4, such as the state of the limit inputs or whether the joystick is connected. See section Status Flags |
|
<EFLAGS> |
Set of flags representing the error state of the SMD4, such as invalid mnemonic, or motor over-temperature fault. See 0 |
|
<CR><LF> |
Message terminator; carriage return followed by line-feed (0x0D,0x0A) |
Addressing
This section is only applicable where multiple SMD4s are connected together on the same bus, using the serial interface in either RS232 or RS485 mode. The addressing logic described in this section works for all interfaces, but is redundant for USB and the network interface since those inherently implement addressing.
When multiple SMD4s exist on the same bus, a mechanism is required to allow them to be addressed uniquely or as a group. Likewise, only one device must use the bus at a time otherwise bus contention results when more than one device tries to drive the bus at a time.
This is accomplished via the address prefix, which is the at '@' symbol followed by a numeric address:
- 0 = Broadcast address, all SMD4s execute the command, but no response is sent
- 1 to 247 = Valid slave address range. The addressed SMD4 executes the command and returns a response
- Any address outside this range is invalid, and the packet is silently ignored
Upon receipt of the first complete packet with an address prefix, the SMD4 enters addressing mode, and behaviour then changes as follows, until restart.
- Malformed packets are silently ignored. This includes any packet that does not include the addressing prefix but that is otherwise valid.
- Broadcast packets are silently parsed and executed. A response is not sent, and as such it cannot be determined whether the command executed successfully without submitting a further query addressed directly to the target SMD4.
- Packets that are otherwise correctly formed but having a target address that does not match that of the SMD4 are silently ignored.
Comma separation
All elements are comma-separated, except for the message terminator which immediately follows the last item. A response is always sent on receipt of a message terminator except where addressing criteria are not met. If an argument was supplied with a command, for example, to set a value, the value set will be returned in the response and serves as an additional confirmation of the command having executed as expected.
Many commands accept a real number argument when the underlying quantity is an integer, or finite set of real numbers. In this case, the supplied value being otherwise acceptable is rounded to the closest integer or real number from the allowed set, and it is this value that is returned in the response.
White space
Additional white space (tabs and spaces) are ignored except where they are surrounded by characters comprising the data item, in which case they will be considered as part of the data item itself.
No data items to return
If there are no data items as part of a response, only the SFLAGS and EFLAGS are returned. If an error occurred, then this will be reflected in the EFLAGS.
Argument types
Arguments may be one or a mix of the following types, depending on the command. Data returned by the SMD4 uses the same types, which are always presented as indicated in the “SMD4 response” column.
|
Type |
Name |
Description |
Example argument values |
SMD3 response |
|
INT |
Integer |
Integer value, with or without sign |
100, -10, +7 |
Sign included for negative values only. E.g. 100, -10 |
|
UINT |
Unsigned integer |
Unsigned integer value, no sign. Hexadecimal representation may also be used, case insensitive |
99, 1000, 0xA74F, 0xd7 |
Numeric format E.g. 100, 200 Except for status and error flags which are returned in upper case 2-byte hexadecimal format, E.g. 0x1234, 0xA4DE |
|
FLOAT |
Real number |
Real number, with or without sign. Scientific format may also be used, case insensitive |
10.23, 100e-3, 100E4, 10 |
Scientific format, with 5 places after the decimal point and a E.g. 1.23000E+04, 5.76159E-10 |
|
STRING |
ASCII string |
ASCII string, consisting of characters 0x20 to 0x7E inclusive |
Abc123 78-%^A |
ASCII string, E.g. “1234 abc”, “10%” |
|
BOOL |
Boolean |
Binary, true/false value |
0, 1 |
E.g. 0, 1 |
Flags
Error flags are reported by the device in hexadecimal format as explained above. E.g. a value of 0x0002 means bit 1 is set (TOPEN), indicating that the device has been disabled due to an open circuit temperature sensor.
Error flags (EFLAGS)
These indicate error conditions and are latching (i.e. remain set even after the error condition that caused them no longer persists). Reset the fault using the clear command, or the reset fault input. The motor is disabled if one or more error flags are set.
|
Bit |
Name |
Description |
|
0 |
Temp Short |
Selected temperature sensor is short-circuited (Not applicable to Thermocouple) |
|
1 |
Temp Open |
Selected temperature sensor is open circuit |
|
2 |
Temp Over |
Selected temperature sensor is reporting temperature > 190 °C and power has been removed from the motor to protect the windings |
|
3 |
Motor Short |
Motor phase to phase or phase to ground short has been detected |
|
4 |
External Disable |
Motor disabled via external input |
|
5 |
Emergency Stop |
Motor disabled via software |
|
6 |
Configuration Error |
Motor configuration is corrupted |
| 7 |
Encoder error |
Encoder fault (applicable only when optional encoder module installed) |
|
8 |
Boost UVLO |
The internal 48 V to 67 V boost circuit is disabled because input voltage has fallen too low. |
|
9 |
SDRAM |
Memory self-test failed. |
|
10-15 |
Reserved |
Reserved, read as ‘0’ |
Status flags (SFLAGS)
|
Bit |
Name |
Description |
|
0 |
Joystick Connected |
Joystick is connected (determined via state of the |
|
1 |
Limit Negative |
Limit input is active (Note that the polarity is configurable, so active can mean high or low signal level) |
|
2 |
Limit Positive |
|
|
3 |
External Enable |
External enable input state |
|
4 |
Ident |
Ident mode is active, green status indicator is flashing to aid in identifying device |
|
5-6 |
Reserved |
Reserved, read as ‘0’ |
|
7 |
Standby |
Motor stationary. Check this bit before performing a function that requires the motor to be stopped first, such as changing mode |
|
8 |
Baking |
Bake mode running |
|
9 |
Target Velocity Reached |
Set when the motor is at target velocity |
|
10 |
Encoder Present |
Encoder module fitted |
|
11 |
Boost Operational |
Internal 48 V to 67 V boost supply is operational |
|
12 |
Boost Disable Jumper |
Set when the hardware boost disable jumper is fitted, preventing the boost supply from operating, see stuff. |
|
13-15 |
Reserved |
Reserved, read as ‘0’ |
Error codes
|
Error |
Description |
|
-1 (Stop motor first) |
Several actions, such as changing resolution or operating mode require that the motor is stopped first. Trying to run such a command before the motor has come to a stop and the standby flag in the status register is set will result in this error. |
|
-2 (Argument validation) |
An argument supplied to the command is invalid, for example, it is outside the allowable range. |
|
-3 (Unable to get) |
The command is write-only, read is not valid. This applies to commands such as RUNV where a read would have no meaning. |
|
-5 (Action failed) |
The command failed to execute due to an internal error, for example, the internal flash in which settings are stored has reached the end of life and data cannot be reliably written to it. |
|
-6 (Not possible in mode) |
The command is not applicable to this mode, for example, trying to start bake using RUNB when not in bake mode. |
|
-7 (Not possible when motor disabled) |
The motor is disabled (due to a fault, or external enable) and the command is one that starts motion, for example RUNV. |
|
-101 (Argument type) |
The argument is of the wrong type, for example a non-integer value was given where an integer value was required. |
|
-102 (Argument count) |
The argument count is incorrect, either too few or too many arguments have been supplied. |
|
-103 (Invalid Mnemonic) |
Command mnemonic is not valid |
|
-104 (Packet error) |
Packet is malformed |
Quick reference
General
|
Mnemonic |
Description |
R |
W |
Arguments |
|
SER |
Read the serial number |
● |
|
|
|
FW |
Read the firmware version number |
● |
|
|
|
CLR |
Clear error flags |
|
● |
|
|
LOAD |
Load saved configuration |
|
● |
|
|
STORE |
Store configuration |
|
● |
|
|
LOADFD |
Load factory defaults |
|
● |
|
|
Identify SMD3 by blinking the status indicator |
|
● |
BOOL |
|
|
Mode of operation |
● |
● |
UINT |
|
|
Joystick mode |
● |
● |
UINT |
|
|
Auto switch to Joystick mode on JS connect |
● |
● |
BOOL |
|
|
External enable used |
● |
● |
BOOL |
|
|
FLAGS |
Returns ascii table of status and error flag states |
● |
|
|
Command movement
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Move motor velocity mode |
|
● |
STRING |
|
|
Move motor absolute positioning mode |
|
● |
INT |
|
|
Move motor relative positioning mode |
|
● |
INT |
|
|
Activate bake mode |
|
● |
|
|
|
Start home mode procedure |
|
● |
STRING |
|
|
Bring motor to a stop according to the current profile |
|
● |
|
|
|
Stop motor in 1 second on full step position independently of the current motion profile |
|
● |
|
|
|
Emergency stop. Stops the motor immediately |
|
● |
|
Motor
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Temperature sensor selection, T/C or RTD |
● |
● |
UINT |
|
|
Temperature in °C |
● |
|
|
|
|
Run current in amps |
● |
● |
FLOAT |
|
|
Acceleration current in amps |
● |
● |
FLOAT |
|
|
Hold current in amps |
● |
● |
FLOAT |
|
|
Power down delay in milliseconds |
● |
● |
FLOAT |
|
|
Power down ramp delay in milliseconds |
● |
● |
FLOAT |
|
|
Freewheel mode |
● |
● |
UINT |
|
|
Resolution |
● |
● |
UINT |
Limit inputs
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Global enable |
● |
● |
BOOL |
|
|
Limit positive (Limit 1) enable |
● |
● |
BOOL |
|
|
Limit negative (Limit 2) enable |
● |
● |
BOOL |
|
|
Limit n polarity (0 for active high, 1 for active low) |
● |
● |
BOOL |
|
|
● |
● |
BOOL |
||
|
Limit polarity for both Limit positive (Limit 1) and negative (Limit 2), (0 for active high, 1 for active low) |
|
● |
BOOL |
|
|
How to stop on limit being triggered |
● |
● |
BOOL |
Profile
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Acceleration in Hz/s |
● |
● |
FLOAT |
|
|
Deceleration in Hz/s |
● |
● |
FLOAT |
|
|
Start frequency in Hz |
● |
● |
FLOAT |
|
|
Stop frequency in Hz |
● |
● |
FLOAT |
|
|
Target step frequency in Hz |
● |
● |
FLOAT |
|
|
Actual frequency in Hz |
● |
|
|
|
|
Actual position in steps |
● |
● |
FLOAT |
|
|
Relative position in steps |
● |
● |
FLOAT |
|
|
Time to stop before moving again in seconds |
● |
● |
FLOAT |
|
|
Full step – micro stepping transition |
● |
● |
FLOAT |
Step/Direction
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Which edges of step input to generate a step on |
● |
● |
UINT |
|
|
Interpolate step input to 256 micro steps |
● |
● |
UINT |
Bake
|
Mnemonic |
Description |
R |
W |
Arguments |
|
Bake temperature setpoint |
● |
● |
UINT |
Command reference
General
SYS:IDENT - Rapidly blinks status indicator (R/W)
Gets or sets a value indicating whether the identify function is enabled. When set to true, the green status light on the front of the product flashes. This can be used to help identify one device amongst several.
|
Query: |
Arguments
The enable state.
|
[0: |
Disable] |
|
1: |
Enable |
Returns
The enable state, as above.
Examples
|
Tx: SYS:IDENT,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: SYS:IDENT<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set ident function on
// Query state of ident function
|
SYS:MODE - Choose mode of operation
Gets or sets the operating mode. See section Operating Modes for an explanation of each mode.
Arguments
The operating mode.
|
0: |
Step/direction |
|
[1: |
Remote] |
|
2: |
Joystick |
|
3: |
Bake |
|
4: |
Home |
Returns
The mode, as above, followed by a space and the name of the mode in brackets.
Remarks
If the motor is moving when attempting to change the mode, a stop motor first error is returned and the mode is unchanged.
Examples
|
Tx: SYS:MODE,2<CR><LF> Rx: 0x0000,0x0000,2 (Remote)<CR><LF> Tx: SYS:MODE<CR><LF> Rx: 0x0000,0x0000,1 (Remote)<CR><LF> |
// Set mode to remote
// Query state of mode
|
SYS:JSMODE – Joystick mode
Gets or sets the joystick mode. Choose between single step, which allows precise single steps or continuous rotation, or continuous which requires only a single button press to make the motor move.
Arguments
The joystick mode.
|
[0: |
Single step] |
|
1: |
Continuous |
Returns
The mode, as above.
Remarks
Set requires the motor to be in standby, otherwise, a stop motor first error will be returned.
In single step mode, a brief button press (< 0.5 s) will execute one step in that direction, while pressing the button for > 0.5 s will cause the motor to accelerate up to slewing speed and continue to rotate in that direction until the button is released, at which point the motor will decelerate to a stop.
In continuous mode, a brief button press will trigger the motor to accelerate up to slewing speed. A subsequent press of the same button causes it to decelerate to a stop. If, for example, the clockwise button is pressed while the motor is rotating anti-clockwise, the motor will first decelerate to a stop before changing direction.
Examples
|
Tx: SYS:JSMODE,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: SYS:JSMODE<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set to continuous
// Query state
|
SYS:AUTOJS – Auto switch to joystick mode
Gets or sets the joystick auto select function. When set to true, the product switches to joystick mode automatically when connecting a joystick.
Arguments
The enable state.
|
0: |
Disable |
|
[1: |
Enable] |
Returns
The enable state, as above.
Examples
|
Tx: SYS:AUTOJS,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: SYS:AUTOJS<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Enable
// Query state
|
SYS:EXTEN – External enable used
Gets or sets a value indicating whether the external enable signal should be respected. If not using the external enable and it remains disconnected, set to false.
Arguments
External enable signal.
|
[0: |
False] |
|
1: |
True |
Returns
True if the external enable signal is used.
Remarks
The external enable input requires a voltage to be applied between SDE COM and EN on the I/O connector which may be inconvenient if you do not wish to use the enable input. In that case, disable the enable input by sending this command with the argument set to false.
Examples
|
Tx: SYS:EXTEN,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: SYS:EXTEN<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Enable
// Query state
|
Command movement
MOTOR:RUNV – Run, velocity
Start continuous rotation in specified direction.
Arguments
Direction:
|
‘+’: |
Positive, step count increases |
|
‘-’: |
Negative, step count decreases |
Remarks
None.
Examples
|
Tx: MOTOR:RUNV,+<CR><LF> Rx: 0x0000,0x0000<CR><LF> Tx: MOTOR:RUNV,-<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Spin motor in positive direction
// Spin motor in negative direction |
MOTOR:RUNA – Run, absolute position
Move the motor to a specified absolute position.
Arguments
|
Minimum: |
-223-1 |
|
Maximum: |
223-1 |
Remarks
None.
Examples
|
Tx: RUNA,1000<CR><LF> Rx: 0x0000,0x0000<CR><LF> Tx: RUNA,-1000<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Start absolute positioning mode, move to the step position 1000 // Start absolute positioning mode to the step position -1000 |
RUNR - Run, relative position
Command to move the motor to a relative position using the positioning mode.
Arguments
|
Minimum: |
-223-1 |
|
Maximum: |
223-1 |
Remarks
Command requires the motor to be in standby, otherwise, a stop motor first error will be returned. Ensure the profile is set.
Examples
|
Tx: RUNR,2000<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: RUNR,-2000<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Start relative positioning mode, move 2000 steps to the positive direction // Start relative positioning mode, move 2000 steps to the negative direction |
RUNB – Run bake
Command to start the bake mode.
Remarks
Set mode to bake first. To stop the bake mode send the STOP command.
Examples
|
Tx: RUNB<CR><LF> Rx: 0x0000,0x0000<CR><LF> Tx: STOP<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Start bake mode
// Stop bake mode |
RUNH – Home to a limit switch
Command to start the home procedure, in which the motor will move in the specified direction until the limit switch for that direction is triggered, at which point a homing procedure is initiated, see section Limits.
Arguments
Direction velocity motion.
|
‘+’: |
Positive |
|
‘-’: |
Negative |
Remarks
Ensure the profile is set and the mode is Home mode.
Examples
|
Tx: RUNH,+<CR><LF> Rx: 0x0000,0x0000<CR><LF> Tx: RUNH,-<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Start homing mode to the positive direction
// Start homing mode to the negative direction |
STOP – Stop motor
Command motor to stop moving according to the current profile.
Remarks
During the deceleration phase that stops the motor, any modifications to the acceleration or deceleration interrupt the stopping phase. Re-send the command to restart the motor stopping phase.
Examples
|
Tx: STOP<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Stop the motor
|
SSTOP – Stop motor in 1 s
Command motor to stop the motion in 1 second.
Remarks
This command does not consider the deceleration set in the profile. Instead, it calculates the deceleration required to stop in 1 second, according to the actual velocity. The motor will stop in a full step position. Steps may be lost if the load requires greater than this duration to stop.
Examples
|
Tx: SSTOP<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Stop the motor in 1 seconds
|
ESTOP – Emergency stop
Command stops immediately and disables the motor. Note that this should not be relied on as a safety interlock.
Remarks
The motor may stop on a fractional step position, but this is irrelevant as motor power is removed and the motor will snap to a full step position. Steps may be lost.
Examples
|
Tx: ESTOP<CR><LF> Rx: 0x0000,0x0000<CR><LF> |
// Stop the motor immediately
|
Motor
TSEL – Temperature sensor selection
AML motors can be ordered with a K-Type thermocouple or a PT100 RTD. Select the correct option for your motor.
Arguments
Motor temperature sensor type.
|
[0: |
Thermocouple] |
|
1: |
RTD |
Returns
Selected temperature sensor type, as above.
Remarks
The drive will not allow the motor to run unless a functioning temperature sensor is connected to the selected sensor connection; be sure to select the correct type.
Examples
|
Tx: TSEL,0<CR><LF> Rx: 0x0000,0x0000,0<CR><LF> Tx: TSEL<CR><LF> Rx: 0x0000,0x0000,0<CR><LF> |
// Select thermocouple sensor
// Queue the state of temperature sensor |
TMOT – Motor temperature
Query the motor temperature.
Returns
Motor temperature in °C, rounded to the nearest 1 °C.
Remarks
The reported temperature is intended only for the purposes of monitoring motor temperature and should not be relied upon for any other purpose within the vacuum system.
Examples
|
Tx: TMOT<CR><LF> Rx: 0x0000,0x0000,25<CR><LF> |
// Query motor temperature // Response is 25 degree Celsius |
IR – Run current
Set or query the motor run current.
Arguments
The motor run current in amps rms.
|
[Default: |
1.044] |
|
Minimum: |
0 |
|
Maximum: |
1.044 |
Returns
The motor run current in amps rms, rounded to the closest multiple of 1.044 A / 31 (approx. 33 mA).
Remarks
IR must be set equal to or smaller than IA. This is enforced by the SMD3; IA is automatically adjusted to be equal to IR, if a change to IR makes it greater than IA.
Examples
|
Tx: IR,1<CR><LF> Rx: 0x0000,0x0000,1.0000E+00<CR><LF> Tx: IR<CR><LF> Rx: 0x0000,0x0000,1.0000E+00<CR><LF> |
// Set run current to 1A
// Query run current
|
IA – Acceleration current
Set or query the motor acceleration/deceleration current.
Arguments
The motor acceleration current in amps rms.
|
[Default: |
1.044] |
|
Minimum: |
0 |
|
Maximum: |
1.044 |
Returns
The motor acceleration current in amps rms, rounded to the closest multiple of 1.044 A / 31 (approx. 33 mA).
Remarks
IA must be set equal to or greater than IR. The SMD3 will not force IA to match IR if IA is smaller than IR.
Examples
|
Tx: IA,1.044<CR><LF> Rx: 0x0000,0x0000,1.0440E+00<CR><LF> Tx: IA<CR><LF> Rx: 0x0000,0x0000,1.0440E+00<CR><LF> |
// Set acceleration current to 1.044 A
// Query acceleration current
|
IH – Hold current
Set or query the motor hold current. If your application allows it, set PDDEL, IHD and IH to zero in order to reduce run current to zero as quickly as possible after stopping which minimises motor temperature rise.
Arguments
The motor hold current in amps rms.
|
[Default: |
0.1] |
|
Minimum: |
0 |
|
Maximum: |
1.044 |
Returns
The motor hold current in amps rms, rounded to the closest multiple of 1.044 A / 31 (approx. 33 mA).
Examples
|
Tx: IH,0.5<CR><LF> Rx: 0x0000,0x0000,5.0000E-01<CR><LF> Tx: IH<CR><LF> Rx: 0x0000,0x0000,5.0000E-01<CR><LF> |
// Set hold current to 0.5A
// Query hold current
|
PDDEL – Power down delay
Set or query the delay time between standstill occurring and the motor current being reduced from the acceleration current to the hold current. Refer to Figure 1. If your application allows it, set PDDEL, IHD and IH to zero in order to reduce run current to zero as quickly as possible after stopping which minimises motor temperature rise.
Arguments
The power-down delay in milliseconds.
|
[Default: |
0] |
|
Minimum: |
0 |
|
Maximum: |
5570 |
Returns
The power-down delay rounded to the closest settable value.
Examples
|
Tx: PDDEL,100<CR><LF> Rx: 0x0000,0x0000,1.0000E+02<CR><LF> Tx: PDDEL<CR><LF> Rx: 0x0000,0x0000, 1.0000E+02<CR><LF> |
// Set PDDEL to 100 ms
// Query PDDEL
|
IHD – Current reduction delay
Set or query the delay per current reduction step that occurs when run current is reduced to hold current. See Figure 1. If your application allows it, set PDDEL, IHD and IH to zero in order to reduce run current to zero as quickly as possible after stopping which minimises motor temperature rise.
Arguments
The delay per current reduction step in milliseconds.
|
[Default: |
0] |
|
Minimum: |
0 |
|
Maximum: |
327 |
Returns
The delay per current reduction step.
Remarks
See also section Going to standby
Examples
|
Tx: IHD,327<CR><LF> Rx: 0x0000,0x0000,3.2700E+02<CR><LF> Tx: IHD<CR><LF> Rx: 0x0000,0x0000,3.2700E+02<CR><LF> |
// Set IHD to 327 ms
// Query IHD
|
F – Freewheel mode
Set or query the freewheel mode. Set the option to use passive braking or freewheeling when the motor is in standby. This feature can be enabled when 'IH' is 0. The desired option becomes active after a time period specified by ‘PDDEL’ and ‘IHD’
Arguments
The freewheel mode:
|
0: |
Normal |
|
1: |
Freewheel |
|
[2: |
Phases shorted to GND] |
Returns
The freewheel mode selection, as above.
Remarks
Use the freewheel mode to allow the motor shaft to spin freely when the motor current is zero. The phases shorted to GND option supplies no power to the motor, but by shorting the phases together a holding torque is produced, and the motor shaft offers considerable resistance to movement. This is enough in many applications to remove the need for any holding current, with the benefit that no heat is generated because the motor phases are not energised.
Examples
|
Tx: F,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: F<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set F to freewheel
// Query state of F
|
RES - Resolution
Set or query the microstep resolution. Although the drive may only stop on full step positions in all modes except step/direction, microstepping is still desirable as it reduces resonances for slow movements. Note that full step resolution is always used above a specified stepping rate, regardless of the resolution set here, see command [THIGH].
Arguments
The microstep resolution as an integer.
|
[Default: |
256] |
|
Possible values: |
8, 16, 32, 64, 128, 256 |
Returns
The microstep resolution, as above.
Remarks
Query is applicable any time, Set requires the motor in standby condition.
The resolution applies globally, including for the step/direction interface. Each step on the step/direction interface generates a 1/8, 1/16, 1/32 etc step according to the resolution set here.
Above a configurable step frequency, the drive switches from the microstepping resolution specified here to full step mode in any case. See section THIGH
Examples
|
Tx: RES,256<CR><LF> Rx: 0x0000,0x0000,256<CR><LF> Tx: RES<CR><LF> Rx: 0x0000,0x0000,256<CR><LF> |
// Set resolution to 256
// Query resolution
|
Limit inputs
L – Limits global enable
Set or query global enable of limits inputs. This does not affect other limits configuration settings, allowing limits to be configured as desired, then globally enabled or disabled if required.
Arguments
Enable state of limits.
|
[0: |
Disable] |
|
1: |
Enable |
Returns
True if limits are globally enabled.
Remarks
This option globally enables or disabled limits; remaining limits settings remain unchanged.
Examples
|
Tx: L,0<CR><LF> Rx: 0x0000,0x0000,0<CR><LF> Tx: L<CR><LF> Rx: 0x0000,0x0000,0<CR><LF> |
// Set global enable of limits to disable
// Query state of global enable of limits
|
L+, L- Individual limit enable
Set or query enable of Lx, where ‘x’ is '+’ or ‘-’.
Arguments
Enable state of limit n.
|
0: |
Disable |
|
[1: |
Enable] |
Returns
True if limit n is enabled.
Remarks
L+ refers to LIMIT 1, associated with movement resulting in incrementing of the position and L- to LIMIT 2, associated with movement decrementing the position counter.
Examples
|
Tx: L+,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: L+<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set positive limit enable
// Query state of positive limit enable
|
LP+, LP- Individual limit polarity
Set or query the polarity of LPx, where ‘x’ is ‘+’ or ‘-’. Limits are active low by default; use this option to make the limit active low.
Arguments
Polarity of LPx.
|
[0: |
Active high] |
|
1: |
Active low |
Returns
The polarity of LPx, as above.
Remarks
LP+ refers to Polarity of LIMIT 1 and LP- to Polarity of LIMIT 2.
Examples
|
Tx: LP-,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: LP-<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set negative limit polarity to active low
// Query state of negative limit polarity
|
LP – Global limit polarity
Set the polarity for both L+ and L-. Limits are active high by default; use this option to make the limit active low.
Arguments
Polarity of LP.
|
[0: |
Active high] |
|
1: |
Active low |
Returns
The polarity of LP, as above.
Remarks
LP+ refers to Polarity of LIMIT 1 and LP- to Polarity of LIMIT 2.
Examples
|
Tx: LP,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: LP-<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: LP+<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set negative and positive limit polarity to active low
// Query state of negative limit polarity
// Query state of positive limit polarity
|
LSM – Limit stop mode
Set or query the stop mode; determines behaviour when a limit is triggered.
Arguments
The stop mode.
|
[0: |
Hard stop; the motor will stop immediately on a limit being triggered] |
|
1: |
Soft stop; the motor decelerates according to the profile |
Returns
The stop mode, as above.
Remarks
When using hard stop, keep in mind that steps may be lost depending on the slewing speed and load on the motor. Treat position counters with caution until the true position has been established. Conversely, when using soft stop, ensure that the motor can decelerate to a stop before the physical end of travel is reached and steps are lost.
Examples
|
Tx: LSM,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: LSM<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set limits stop mode to soft stop
// Query state of limits stop mode
|
Profile
AMAX - Acceleration
Set or query the acceleration, in Hz/s (steps per second per second)
Arguments
The acceleration in Hz/s.
|
[Default: |
5000] |
|
Minimum: |
Where resolution is the microstep resolution 8, 16, 32, 64, 128 or 256 |
|
Maximum: |
Where resolution is the microstep resolution 8, 16, 32, 64, 128 or 256 |
Returns
The user-defined AMAX (data 1) and the real value after the conversion (data 2).
Remarks
Notice that the maximum acceleration depends on the motor resolution. Therefore, when changing resolution, the SMD3 validates the acceleration value and may change it if necessary, to constrain it according to the above equation.
Examples
|
Tx: AMAX,150<CR><LF> Rx: 0x0000,0x0000,1.5000E+02,1.4988E+02<CR><LF> Tx: AMAX<CR><LF> Rx: 0x0000,0x0000,1.5000E+02,1.4988E+02<CR><LF> |
// Set acceleration to 150Hz/s
// Note that the target value of 150 has been adjusted to the closest real value, which deviates from the requested value by 0.12 Hz/s |
DMAX - Deceleration
Set or query the deceleration, in Hz/s (steps per second per second)
Arguments
The deceleration in Hz/s.
Returns
The user-defined DMAX (data 1) and the real value after the conversion (data 2).
Remarks
Notice that the maximum deceleration depends on the motor resolution. Therefore, when changing resolution, the SMD3 validates the deceleration value and may change it if necessary, to constrain it according to the above equation.
Examples
|
Tx: DMAX,150<CR><LF> Rx: 0x0000,0x0000,1.5000E+02,1.4988E+02<CR><LF> Tx: DMAX<CR><LF> Rx: 0x0000,0x0000,1.5000E+02,1.4988E+02<CR><LF> |
// Set deceleration to 150Hz/s
// Query deceleration
|
VSTART – Start frequency
Set or query the start frequency in Hz.
The start frequency is the initial step rate, and helps to allow the motor to overcome inertia and start moving smoothly; if start frequency were zero, the duration of the initial few steps might be long enough that the motor would overcome inertia on the first step, then effectively stop for a time, then have to overcome inertia once more for the second step, and so on, until the steps were frequent enough that the motor remains moving.
Arguments
The start frequency in Hz.
Returns
The user-defined VSTART (data 1) and the real value after the conversion (data 2).
Remarks
VSTART must be set equal to or less than VSTOP. This is enforced by the SMD3; if a change to VSTART makes it bigger than VSTOP, VSTOP is automatically adjusted to be equal to VSTART.
VSTART must be set equal to or less than VMAX. The SMD3 will not force VSTART to match VMAX if VSTART is greater than VMAX.
Examples
|
Tx: VSTART,0<CR><LF> Rx: 0x0000,0x0000,0.0000+00,0.0000+00<CR><LF> Tx: VSTART<CR><LF> Rx: 0x0000,0x0000,0.0000+00,0.0000+00<CR><LF> |
// Set VSTART to 0 Hz
// Query VSTART |
VSTOP – Stop frequency
Set or query the stop frequency in Hz.
The stop frequency is the frequency at which the deceleration ramp ends; i.e. the deceleration ramp does not go from the target frequency linearly down to 0, but from the target frequency linearly down to the stop frequency.
Arguments
The stop frequency in Hz.
Returns
The user-defined VSTOP (data 1) and the real value after the conversion (data 2).
Remarks
VSTOP must be set equal to or greater than VSTART. This is enforced by the SMD3; if a change to VSTOP makes it smaller than VSTART, VSTART is automatically adjusted to be equal to VSTOP.
VSTOP must be set equal to or less than VMAX. The SMD3 will not force VSTOP to match VMAX if VSTOP is greater than VMAX.
Examples
|
Tx: VSTOP,10<CR><LF> Rx: 0x0000,0x0000,1.0000+01,9.9996+00<CR><LF> Tx: VSTOP<CR><LF> Rx: 0x0000,0x0000,1.0000+01,9.9996+00<CR><LF> |
// Set VSTOP to 10 Hz
// Query VSTOP |
VMAX – Step frequency
Set or query the target frequency, in Hz. This is the maximum speed the motor will be run at. The target frequency will only be reached if there is enough time or distance to do so; if moving for a short time, for example, the motor may only accelerate to some fraction of the target frequency before it is time to decelerate to a stop.
Arguments
The target frequency in Hz.
|
[Default: |
1 kHz] |
|
Minimum: |
1 Hz |
|
Maximum: |
15 kHz |
Returns
The user-defined VMAX (data 1) and the real value after the conversion (data 2).
Remarks
Motor torque decreases with speed, and each motor will have a different maximum frequency that it can achieve while reliably maintaining synchronicity (when synchronicity is lost, the motor fails to complete the steps that it is commanded to, leading to a difference between the true and actual positions), depending on the load it is driving.
VMAX must be set equal to or greater than VSTART and VSTOP. The SMD3 will not force VMAX to match VSTART and VSTOP if VMAX is smaller than VSTART and VSTOP.
Examples
|
Tx: VMAX,1000<CR><LF> Rx: 0x0000,0x0000,1.0000E+03,1.0000E+03<CR><LF> Tx: VMAX<CR><LF> Rx: 0x0000,0x0000,1.0000E+03,1.0000E+03<CR><LF> |
// Set VMAX to 1 kHz
// Query VMAX |
VACT – Actual frequency
Query the actual frequency (the frequency at which the motor is currently spinning) in Hz (steps per second).
Returns
The frequency at which the motor is spinning in Hz.
Remarks
This value is derived from the stepper motor control logic, there is no feedback from the motor itself. Hence, the motor could be stalled while VACT continues to indicate the expected.
Examples
|
Tx: VACT<CR><LF> Rx: 0x0000,0x0000,1.0000E+03<CR><LF> |
// Query state of blink |
PACT – Actual position
Set or query the actual position in steps.
The usual way to position the motor is to initialise the actual position to some reference value, usually 0, then adjust the target position to move the motor. In this way, by setting RUNA to 0 the motor can be homed to the initial 0 position. If you wish to perform relative movements, while still retaining an absolute reference, see PREL command.
Arguments
The target position in steps.
|
[Default: |
0] |
|
Minimum: |
-223 |
|
Maximum: |
223-1 |
Returns
The absolute position, as above.
Remarks
Query is applicable any time, Set requires the motor in standby condition.
Examples
|
Tx: PACT<CR><LF> Rx: 0x0000,0x0000,1000.00<CR><LF> Tx: PACT,0<CR><LF> Rx: 0x0000,0x0000,0.00<CR><LF> |
// Query actual position
// Set actual position 0 |
PREL – Relative position
Set or query the relative position in steps.
Use this function to perform relative movement, while still retaining reference to absolute position via PACT. Set the desired value then use the RUNR command to initiate movement.
Arguments
The target position in steps.
|
[Default: |
0] |
|
Minimum: |
-223 |
|
Maximum: |
223-1 |
Returns
The relative position, as above.
Remarks
Query is applicable any time. Set requires the motor in standby condition.
Examples
|
Tx: PREL<CR><LF> Rx: 0x0000,0x0000,1000.00<CR><LF> Tx: PREL,0<CR><LF> Rx: 0x0000,0x0000,0.00<CR><LF> |
// Query relative position
// Set relative position 0 |
TZW – Zero wait time
Set or query the waiting time after ramping down to a stop before the next movement can start.
When using higher values for the start and stop frequency, a subsequent move in the opposite direction would result in a jerk equal to VSTART + VSTOP. The motor may not be able to follow this. TZW can be used to introduce a short delay between the two and eliminate the jerk.
Arguments
The waiting time in milliseconds.
|
[Default: |
0] |
|
Minimum: |
0 |
|
Maximum: |
2796 |
Returns
The zero wait time, as above.
Examples
|
Tx: TZW,100<CR><LF> Rx: 0x0000,0x0000,1.0000E+02<CR><LF> Tx: TZW<CR><LF> Rx: 0x0000,0x0000,1.0000E+02<CR><LF> |
// Set TZW to 100 ms
// Query TZW |
THIGH – Microstep transition
Set or query the full step / microstepping transition. When frequency falls below this threshold (approximately), the motor switches from full step to the selected microstep resolution. The SMD3 determines the upper threshold automatically and applies hysteresis to avoid possible jitter between the two stepping modes. The upper threshold cannot be adjusted.
Arguments
Threshold in frequency Hz.
|
[Default: |
10000 Hz] |
|
Minimum: |
1 Hz |
|
Maximum: |
15000 Hz |
Returns
The user-defined THIGH (data 1) and the real value after the conversion (data 2)
Remarks
The SMD3 software calculates and displays the upper threshold value for reference, although as noted above it cannot be adjusted.
Examples
|
Tx: THIGH,500<CR><LF> Rx: 0x0000,0x0000,5.0000E+02,5.0400E+02<CR><LF> Tx: THIGH<CR><LF> Rx: 0x0000,0x0000,5.0000E+02,5.0400E+02<CR><LF> |
// Set THIGH threshold to 500 Hz
// Query THIGH |
Step/Direction
EDGE – Edge to step on
Set or query a value indicating whether a step occurs on both the rising and falling edges of the step input, or just the rising edge.
Arguments
Step on both edges.
[0: Rising edge only; a step occurs only on the rising edge]
1: Both; a step occurs on both rising and falling edges
Returns
True if step input is configured to step on both rising and falling edges, as above.
Remarks
Enabling this feature halves the clock rate required to achieve a chosen step rate. The EDGE command is disabled in any other modes than step/direction mode.
Examples
|
Tx: EDGE,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: EDGE<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set EDGE to rising edge
// Query EDGE |
INTERP – Step interpolation
Set or query a value indicating whether the step input should be interpolated to 256 microsteps.
Arguments
Enable interpolation of step input to 256 microsteps.
|
[0: |
Normal; each step input will cause one step at the current resolution] |
|
1: |
Interpolate; each step input will be interpolated to 256 microsteps. |
Returns
True if interpolation mode is active, as above.
Remarks
The INTERP command is useful in step/direction mode. Enabling this feature affords the benefits of high-resolution microstepping, without the drawback of very high step clock rates. Internal logic tracks the rate at which steps are supplied and smooths them out into 256 microsteps.
Examples
|
Tx: INTERP,1<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> Tx: INTERP<CR><LF> Rx: 0x0000,0x0000,1<CR><LF> |
// Set interpolation to 256 microstep on
// Query INTERP |
Bake
BAKET – Bake temperature setpoint
Set or query the bake temperature setpoint. To run bake, select bake mode using the MODE, then start bake using RUNB. Use STOP to end bake.
Arguments
Bake temperature setpoint.
|
[Default: |
150 °C] |
|
Minimum: |
0 °C |
|
Maximum: |
200 °C |
Returns
Bake temperature setpoint in °C, as above.
Examples
|
Tx: BAKET,100<CR><LF> Rx: 0x0000,0x0000,100<CR><LF> Tx: BAKET<CR><LF> Rx: 0x0000,0x0000,100<CR><LF> |
// Set bake setpoint to 100 °C
// Query BAKET |