# Menu 31 − AMC General Set-up

Mode: RFC‑A

System components

The diagram below shows the format and interface for the Advance Motion Controller.

The Advanced Motion Controller includes its own profile generator and combines the speed feed-forwards from the profile with the output of its position control loop to give a single speed reference in 0.1rpm or 0.1mm/s units. The conversion to the output speed is based on the set-up parameters of the position feedback selected to control the motor.

The Advanced Motion Controller is made up from the components shown in the diagram below. Individual menus are provided for each of the components.

Function | Description
Master Position | The master position can be used as the input to the Cam or electronic gearbox functions and can be derived as follows: From a position feedback interface in the drive or a position feedback interface in an option module. As a speed (normally fixed) so that it can be used to create a time based profile. As a user position value from a parameter.
Slave Position | The slave position is used as the feedback for the position control loop and can be derived as follows: From a position feedback interface in the drive or a position feedback interface in an option module. As a user position value from a parameter.
Reference selector | The reference selector is used to select the input to the profile generator. In addition to the output from the Cam or electronic gearbox functions, a position or speed reference can be selected. The stop reference is a position that is constantly updated to provide a target when the system is to stop under the constraints of the profile generator. The homing system can provide a reference at the input to the profile generator during a homing routine.
Cam | The Cam function uses a table to define the movement of the slave with respect to the master. The Cam table consists of a number of segments. Interpolation functions are provided to define the type of movement required by the slave within each segment.
Cam Table | The Cam table is used by the Cam to define the required movement of the slave in response to the movement of the master.
Electronic gearbox | The electronic gearbox allows the slave to be locked to the master including a gearbox ratio. The profile generator is used during the transition between the unlocked and locked states to control the acceleration of the slave.
Profile generator | The input to the profile generator is a target that it attempts to attain within the required constraints. These constraints include the maximum linear acceleration/deceleration, jerk and speed. The target for the profile generator can be a position, a speed, or a position and a speed. The outputs of the profile generator include a speed that is used directly as a speed feed-forward term, acceleration that is used to derive the torque or acceleration feed-forward terms and a position that is used as the input to a position control loop.
Position control loop | The position control loop modifies the motion controller output speed to correct the slave position and compensate for deviations from the required profile due to control system and load effects.
Homing system | The homing system can move the slave under the constraints of the profile generator to find the home position. Once the home position is detected the system can be offset so that the required position is seen at the homing point.
Control and status | The control and status system provides overall control for the motion controller and gives status information with a number of flags.

Position units

Position feedback from a drive or option module position feedback interface is given as a 32 bit signed value (normalised position) including the effect of the marker input for the interface (if relevant). The number of bits that represent turns (for a rotary position feedback device) or motor poles (for a linear position feedback device) can be selected for each position feedback device with a parameter in the set-up menu for that interface. Position is represented in the Advanced Motion Controller as a 32 bit signed value. Conversion ratios can be applied to the master position (AMC Master User Units Ratio Numerator (31.004) / AMC Master User Units Ratio Denominator (31.005)), the slave position (AMC Slave User Units Ratio Numerator (31.006) / AMC Slave User Units Ratio Denominator (31.007)) and the motion controller output (AMC Output User Units Ratio Numerator (31.008) / AMC Output User Units Ratio Denominator (31.009)). The slave position can be provided by the encoder used to control the motor or from an additional encoder attached to the load (i.e. dual loop configuration) as shown below.

The input ratios should be used to convert the normalised master and slave position to the required user units used for position within the motion controller and the output ratio should be setup to convert from user units to the normalised position units for the feedback device used to control the motor. If the slave feedback is derived from the position feedback used to control the motor the output ratio will be the inverse of the slave ratio. In a dual loop configuration the output ratio must be setup to correct for any differences between the configuration of the normalised units and the speed of the slave (load) and motor feedback, i.e. mechanical gearing. The conversion from position units to user units (input ratio) and from user units back into position units (output ratio) is demonstrated in the following examples. In these examples the parameter references refer to a feedback device connected to the drives P1 or P2 interface but any drive or option module interface can be used.

Example 1 - Rotary encoder

Position feedback configuration and user units requirements:

- The normalised position for the slave position feedback has 16 P1 Normalisation Turns (03.057) and 16 position bits
- One revolution of the slave gives a movement of 1m
- User units are to represent an item that is 3.57cm long with a resolution of 3 decimal places (1 user unit = 3.57cm/1000 = 35.7μm)

The slave user units ratio can be setup to convert the 32 bit normalised position into 35.7μm units as follows:

- Change of user units over the required range = 1m / 35.7-6m = 107 / 357
- Change of normalised position over the required range = 2Position bits

AMC Slave User Units Ratio Numerator (31.006) = 107

AMC Slave User Units Ratio Denominator (31.007) = 216 x 357 = 23396352

The output ratio is the inverse of the input ratio:

AMC Output User Units Ratio Numerator (31.008) = 216 x 357 = 23396352

AMC Output User Units Ratio Denominator (31.009) = 107

Example 2: Linear Encoder

Position feedback configuration and user units requirements:

- The normalised position for the slave position feedback has 8 P1 Normalisation Turns (03.057) and 24 position bits.
- 64 poles correspond to a linear movement of 10m (P1 Pole Pitch (03.055) = 1000 x 10 / 64 = 156.25 mm).
- The position units require a resolution of 1μm.

The slave user units ratio can be setup to convert the 32 bit normalised position into 0.001mm units as follows:

- Change of user units over the required range = 10m / 10-6m = 107
- Change of normalised position over the required range = 64 x 2Position bits = 230

AMC Slave User Units Ratio Numerator (31.006) = 107

AMC Slave User Units Ratio Denominator (31.007) = 230

The output ratio is the inverse of the input ratio:

AMC Output User Units Ratio Numerator (31.008) = 230

AMC Output User Units Ratio Denominator (31.009) = 107

Example 3 - Rotary encoders with different motor and slave feedback devices (i.e. dual loop configuration)

Position feedback configuration and user units requirements:

- The normalised position for the slave position feedback has 12 P1 Normalisation Turns (03.057) and 20 position bits
- The normalised position for the motor feedback has 16 P2 Normalisation Turns (03.157) and 16 position bits
- User units are to represent one revolution in degrees with three decimal places (1 revolution = 360000 user units)
- There is a gear ratio of 16:1 between the motor and slave feedback

The slave user units ratio can be setup to convert the 32 bit normalised position into 0.001 degree units as follows:

- Change of user units over the required range = 360000
- Change of normalised position over the required range = 220

AMC Slave User Units Ratio Numerator (31.006) = 360000

AMC Slave User Units Ratio Denominator (31.007) = 220

In this example the output ratio is setup to convert from user units to the normalised position units for the motor feedback and must include the inverse of the gear ratio to ensure that the required output speed is seen at the slave feedback.

AMC Output User Units Ratio Numerator (31.008) = 216 x 16

AMC Output User Units Ratio Denominator (31.009) = 360000

Speed units

Speed parameters are 32 bit values specified in User units/ms with a range from -231 to 231-1. The speed parameters have two decimal places. If PosBits are the number of bits representing the number of counts per revolution for a rotary position feedback device then the speed resolution is calculated as follows:

Speed resolution

> > > > = 0.01 user units/ms
> > > > = (0.01 / User units ratio) PosBits/ms
> > > > = (0.01 / 2PosBits / User units ratio) revs/ms
> > > > = (10 / 2PosBits / User units ratio) revs/s
> > > > = (600 / 2PosBits / User units ratio) rpm

If PosBits are the number of bits representing the counts per pole pitch (PolePitch) for a linear feedback device then the speed resolution is calculated as follows:

Speed resolution

> > > > = 0.01 user units/ms
> > > > = (0.01 / User units ratio) PosBits/ms
> > > > = (0.01 / 2PosBits / User units ratio) poles/ms
> > > > = (0.01 x PolePitch / 2PosBits / User units ratio) mm/ms
> > > > = (10 x PolePitch / 2PosBits / User units ratio) mm/s

The speed resolution and the maximum speed can be calculated using the equations in the table below.

Speed | Calculation | Units
Resolution with rotary position feedback device | (600 / 2PosBits) / User units ratio | rpm
Maximum speed with rotary position feedback device | Resolution x 231-1 | rpm
Resolution with linear position feedback device | (10 x PolePitch / 2PosBits) / User units ratio | mm/s
Maximum speed with linear position feedback device | Resolution x 231-1 | mm/s

The resolution can be used to relate the parameter value to the speed of the position feedback device as follows.

Speed parameter value = Speed of position feedback device / Resolution

The table below shows the speed resolution and the maximum possible speed for a rotary application in rpm and for a linear application with a pole pitch of 50mm in mm/s with a user units ratio of unity. A user units ratio of more than unity will not change the resolution, but a user units ratio of less than unity will make the resolution coarser.

Turns bits | Position bits | Resolution (rpm) | Maximum speed (rpm) | Resolution (mm/s) | Maximum speed (mm/s)
8 | 24 | 3.58x10-5 | 7.68x104 | 2.98x10-5 | 6.40x104
12 | 20 | 5.72x10-4 | 1.23x106 | 4.77x10-4 | 1.02x106
16 | 16 | 9.16x10-3 | 1.97x107 | 7.63x10-3 | 1.64x107
20 | 12 | 1.46x10-1 | 3.15x108 | 1.22x10-1 | 2.62x108
24 | 8 | 2.34 | 5.03x109 | 1.95 | 4.19x109

To allow the profile generator to work at the minimum acceleration (0.001 user units/ms/ms) the internal speed resolution used by the profile generator is defined by the minimum acceleration unit. When the profile generator is enabled (AMC Profile Disable (38.005) = 0) the maximum speed can be limited by the output of the profile generator. As above, the maximum profile speed is calculated from the speed resolution and the internal speed resolution of the profile generator is calculated as follows:

Profile speed resolution = Speed resolution / 10.24 x (1ms / AMC Rate Selected (31.013))

The table below shows the internal profile speed resolution and the maximum speed when AMC Rate Selected (31.013) = 250μs.

Turns bits | Position bits | Profile Internal Resolution (rpm) | Profile Maximum Speed (rpm) | Profile Internal Resolution (mm/s) | Profile Maximum Speed (mm/s)
8 | 24 | 8.73x10-7 | 1.87x103 | 7.28x10-7 | 1.56x103
12 | 20 | 1.40x10-5 | 3.00x104 | 1.16x10-5 | 2.50x104
16 | 16 | 2.24x10-4 | 4.80x105 | 1.86x10-4 | 4.00x105
20 | 12 | 3.58x10-3 | 7.68x106 | 2.98x10-3 | 6.40x106
24 | 8 | 5.72x10-2 | 1.23x108 | 4.77x10-2 | 1.02x108

If a higher maximum profile speed is required the resolution can be decreased by using a user unit ratio less than unity or AMC Rate Selected (31.013) can be increased.

Acceleration units

Acceleration parameters are 32 bit values specified in User units/ms/ms with a range from 0 to 230 - 1. The acceleration parameters have 4 decimal places. If PosBits are the number of counts per revolution for a rotary position feedback device then the acceleration resolution is calculated as follows:

Acceleration resolution

> > > > = 0.001 user units/ms/ms
> > > > = (0.001 / User units ratio) PosBits/ms/ms
> > > > = (0.001 / 2PosBits / User units ratio) revs/ms/ms
> > > > = (1000 / 2PosBits / User units ratio) revs/s/s
> > > > = (60000 / 2PosBits / User units ratio) rpm/s

If PosBits are the number bits representing the counts per pole pitch (PolePitch) for a linear feedback device then the acceleration resolution is calculated as follows:

Acceleration resolution

> > > > = 0.001 user units/ms/ms
> > > > = (0.001 / User units ratio) PosBits/ms/ms
> > > > = (0.001 / 2PosBits / User units ratio) poles/ms/ms
> > > > = (0.001 x PolePitch / 2PosBits / User units ratio) mm/ms/ms
> > > > = (1000 x PolePitch / 2PosBits / User units ratio) mm/s2

The acceleration resolution and the maximum acceleration can be calculated using the equations in the table below.

Acceleration | Calculation | Units
Resolution with rotary position feedback device | (60000 / 2PosBits) / User units ratio | rpm/s
Maximum acceleration with rotary position feedback device | Resolution x 230-1 | rpm/s
Resolution with linear position feedback device | (1000 x PolePitch / 2PosBits) / User units ratio | mm/s2
Maximum acceleration with linear position feedback device | Resolution x 230-1 | mm/s2

The resolution can be used to relate the parameter value to the acceleration of the position feedback device as follows:

Acceleration parameter value = Acceleration of position feedback device / Resolution

The table below shows the minimum and maximum time that can be set up to acceleration from zero to 3000rpm for a rotary application and zero to 1m/s for a linear application with a user units ratio of unity. A user units ratio of more than unity will not change the resolution, but a user units ratio of less than unity will make the resolution coarser.

Turns bits | Position bits | Maximum acceleration time to 3000rpm (s) | Minimum acceleration time to 3000rpm (s) | Maximum acceleration time to 1ms-1 (s) | Minimum acceleration time to 1ms-1 (s)
8 | 24 | 8.39x105 | 7.81x10-4 | 3.36x105 | 3.13x10-4
12 | 20 | 5.24x104 | 4.88x10-5 | 2.10x104 | 1.95x10-5
16 | 16 | 3.28x103 | 3.05x10-6 | 1.31x103 | 1.22x10-6
20 | 12 | 2.05x105 | 1.91x10-7 | 8.19x101 | 7.63x10-8
24 | 8 | 1.28x101 | 1.19x10-8 | 5.12 | 4.77x10-9

Parameter | 31.001 AMC Select
--- | ---
Short description | Set to 1 to write the output of the motion controller to the Hard Speed Reference
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

When the Advanced Motion Controller is selected (i.e. AMC Select (31.001) = 1) the output of the motion controller is written to Hard Speed Reference (03.022). The table below shows the effect of changing the value of AMC Select (31.001).

AMC Select (31.001) | Action
0 | On changing from 1 to 0: Hard Speed Reference (03.022) = 0 Hard Speed Reference Select (03.023) = 0
1 | On changing from 0 to 1: Hard Speed Reference (03.022) = AMC Output Speed (39.012) Hard Speed Reference Select (03.023) = 1

If Hard Speed Reference Select (03.023) is turned off after the motion controller has been initialised the motion controller will operate as expected but AMC Output Speed (39.012) will not be written to Hard Speed Reference (03.022). If the motion controller is not selected (i.e. AMC Select (31.001) = 0) none of the functionality in menu 31 to menu 41 is enabled.

Parameter | 31.002 AMC Absolute Mode Enable
--- | ---
Short description | Set to 1 to enable the absolute mode of the advance motion controller
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

AMC Absolute Mode Enable (31.002) defines how the position feedback information is transferred to the integrators for the master and slave source positions.

If AMC Absolute Mode Enable (31.002) = 0 then the integrators are either held at zero (AMC Incremental Position Reset Mode (31.003) = 0), or continue to operate normally (AMC Incremental Position Reset Mode (31.003) = 1), when the motion controller is disabled. (See AMC Enable (41.001) for details on how to enable or disable the motion controller.) Therefore both the master and slave positions are incremental relative to zero when the motion controller is enabled or when the drive was powered up respectively. When the motion controller is enabled the change of position from the position feedback device is modified by the user unit ratio, and inverted if required, before being accumulated in the integrator.

If AMC Absolute Mode Enable (31.002) = 1 then the position is taken from the position feedback device, modified by the user units ratio, inverted if required and then written to the integrator when the motion controller is initialised or any parameter which results in a change of absolute position is modified. After the feedback has been initialised the change of position from the position feedback device is modified by the user unit ratio, and inverted if required, before being accumulated in the integrator when the motion controller is enabled or disabled. If the user unit ratio is above unity the master and slave position integrators can rollover the boundary during initialisation. When AMC Roll-over Limit (31.010) > 0 the initialisation of the slave position is handled differently to allow the position within the rollover limit to be recovered correctly after the normalised position or the internal user position has rolled over a boundary, see AMC Roll-over Limit (31.010).

Parameter | 31.003 AMC Incremental Position Reset Mode
--- | ---
Short description | If set to 0 the integrators are held at zero when the AMC is disabled, and if set to 1 the integrators continue to operate normally when the AMC is disabled
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Absolute Mode Enable (31.002).

Parameter | 31.004 AMC Master User Units Ratio Numerator
--- | ---
Short description | Defines the numerator of the AMC Master User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

The master user units ratio (AMC Master User Units Ratio Numerator (31.004) / AMC Master User Units Ratio Denominator (31.005)) is applied to the master position to convert the feedback position from normalised units to user units. Similar ratios are provided for the slave position and the output of the motion controller. The configuration of these ratios is described in AMC General Set-up (31).

Parameter | 31.005 AMC Master User Units Ratio Denominator
--- | ---
Short description | Defines the denominator of the AMC Master User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Master User Units Ratio Numerator (31.004).

Parameter | 31.006 AMC Slave User Units Ratio Numerator
--- | ---
Short description | Defines the numerator of the AMC Slave User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Master User Units Ratio Numerator (31.004).

Parameter | 31.007 AMC Slave User Units Ratio Denominator
--- | ---
Short description | Defines the denominator of the AMC Slave User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Master User Units Ratio Numerator (31.004).

Parameter | 31.008 AMC Output User Units Ratio Numerator
--- | ---
Short description | Defines the numerator of the AMC Output User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Master User Units Ratio Numerator (31.004).

Parameter | 31.009 AMC Output User Units Ratio Denominator
--- | ---
Short description | Defines the denominator of the AMC Output User Units Ratio
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default | 1000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See AMC Master User Units Ratio Numerator (31.004).

Parameter | 31.010 AMC Roll-over Limit
--- | ---
Short description |
Mode | RFC‑A
Minimum | 0 | Maximum | VM_AMC_ROLLOVER
Default | 0 | Units | UU
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW, VM

If AMC Roll-over Limit (31.010) = 0 the motion controller operates over a range from -231 to 231-1, i.e. VM_AMC_POSITION[MIN] = -231 and VM_AMC_POSITION[MAX] = 231-1, and the system can rollover the VM_AMC_POSITION[MIN] and VM_AMC_POSITION[MAX] boundaries without a transient. When AMC Roll-over Limit (31.010) is set to a non-zero value the motion controller continues to operate over a range from -231 to 231-1 internally but the position parameters display a position from zero to AMC Roll-over Limit (31.010) - 1, i.e. VM_AMC_POSITION[MIN] = 0 and VM_AMC_POSITION[MAX] = AMC Roll-over Limit (31.010) - 1, and the system can rollover the zero or VM_AMC_POSITION[MAX] boundaries without a transient. Note that when AMC Auto Resolution Enable (31.015) is enabled VM_AMC_ROLLOVER[MAX] = 230-1 / AMC Auto Resolution Scaling (31.016).

When AMC Absolute Mode Enable (31.002) = 0 the position parameters are always set to zero during initialisation. When AMC Absolute Mode Enable (31.002) = 1 the absolute slave position is recovered from the user and normalised positions saved on power down. This allows an absolute encoder to be homed once and for the correct position within the rollover limit to be recovered after the internal user position or the normalised position has rolled over the minimum or maximum boundary one or more times. Note that the correct absolute position will only be recovered if the normalised position has moved by less than half of the maximum range when the drive is off and absolute mode is enabled when the motion controller is initialised. Note that when using the control word to configure the absolute mode AMC Control Word Enable (41.021) should be set to mode 2 to ensure the absolute position is recovered correctly during initialisation. The master position is always initialised with the absolute position calculated using the normalised position and the master user unit ratio. The initial position (AMC Master Position (32.004)) within the rollover limit is derived from this position as shown in the diagram below.

When AMC Absolute Mode Enable (31.002) is enabled the slave position is initialised using the same method as the master position, but after the internal user or normalised positions have rolled over one of the boundaries the slave position may no longer be directly related to the normalised position of the feedback device.

Parameter | 31.011 AMC Synchronise To Onboard User Program Clock Task
--- | ---
Short description | Set to 1 to allow the AMC to be controlled synchronously by an onboard user program clock task
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

Most time critical parts of the Advanced Motion Controller operate at the sample rate set in AMC Rate Select (31.012). The homing function and most parameter access operate at a 4ms rate. The timing of the controller (AMC Rate Select (31.012) = 250μs) and parameter reading and writing is shown below with respect to other tasks in the drive.

The following examples show how the Advanced Motion Controller can be controlled in different configurations. Note that AMC Synchronise To Onboard User Program Clock Task (31.011) should only be enabled when the onboard user program is writing to one of the parameters updated at the beginning of every motion controller task.

Stand-alone motion controller

Most parameters are set up during commissioning and are not time critical. AMC Action On Event (34.008) can be used to set up triggered time critical events, or the position and speed references can be controlled via communications from an external controller.

Simple position control loop with option module providing the rest of the motion controller

AMC External Position Reference (39.002), AMC External Speed Reference (39.004) and AMC External Acceleration Reference (39.014) can be used by an option module as the references for a simple position control loop. These values should be updated outside the active period of the motion controller.

Motion controller controlled by an option module

AMC Master User Position Reference (32.009), AMC Slave User Position Reference (33.009), AMC Position Reference (34.003), AMC Speed Reference (34.006) and AMC Reference Select (34.007) can be modified every 250μs and should be updated outside the active period of the motion controller. AMC Action On Event (34.008) can be used to set up triggered time critical events.

Motion controller controlled by an on-board user program

All 250μs read parameters are cached for use by the motion controller at the start of the thread where the user program timed task will be started and not at the start of every thread in which the motion controller runs. This means that the values that were updated during the previous timed task are read together.

Parameter | 31.012 AMC Rate Select
--- | ---
Short description | Defines the sample rate of the AMC
Mode | RFC‑A
Minimum | 1 | Maximum | 5
Default | 5 | Units |
Type | 8 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW, TE

Value | Text
1 | 4ms
2 | 2ms
3 | 1ms
4 | 500us
5 | 250us

AMC Rate Selected (31.013) indicates whether the Advanced Motion Controller is active or not, and the sample rate being used. The sample rate for the Advanced Motion Controller is selected with AMC Rate Select (31.012). It should be noted that both the Advanced and Standard motion controllers cannot be active at the same time and can only be enabled or disabled when the drive is in the disabled state. If both motion controllers are selected at power-up the Standard Motion Controller will take priority.

The sample rate of the Advanced Motion Controller is limited in each of conditions shown in the table below. If more than one of the conditions is active the motion controller will operate at the slower of the two update rates, i.e. if an option module is used to provide the position feedback and an s-ramp profile is enabled then AMC Rate Selected (31.013) is limited to 1ms.

Mode | Description | Maximum sample rate
AMC Master Source Select (32.001) ≥ 4 | Option module feedback interface | 500μs
AMC Slave Source Select (33.001) ≥ 4 | Option module feedback interface | 500μs
AMC Roll-over Limit (31.010) > 0 |  | 500μs
AMC Profile Jerk 1 (38.011) > 0 | S-ramp profile active | 1ms
Sensorless Mode Active (03.078) = On (1) |  | 4ms

Parameter | 31.013 AMC Rate Selected
--- | ---
Short description | Shows the actual sample rate of the AMC
Mode | RFC‑A
Minimum | 0 | Maximum | 5
Default |  | Units |
Type | 8 Bit Volatile | Update Rate | Background write
Display Format | Standard | Decimal Places | 0
Coding | RO, TE, ND, NC, PT

Value | Text
0 | Not Active
1 | 4ms
2 | 2ms
3 | 1ms
4 | 500us
5 | 250us

See AMC Rate Select (31.012).

Parameter | 31.014 AMC Speed Mode Enable
--- | ---
Short description | Set to 1 to enable speed mode
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

Speed mode is active when AMC Speed Mode Enable (31.014) = 1 and AMC Reference Select (34.007) = 2 (speed reference). When speed mode is active AMC Profile Maximum Speed (38.003) is ignored, AMC Profile Input Position (38.006) and AMC Profile Output Position (38.008) are set to AMC Slave Position (33.004) at the beginning of each sample and AMC Position Error (39.008) is held at zero. If AMC Position Error (39.008) is not zero when speed mode is activated AMC Position Error (39.008) x AMC Position Control Loop Kp Gain (39.007) / 1000 (clamped by AMC Output Speed Clamp (39.011)) is added to AMC Profile Output Speed (38.009) to prevent a transient in AMC Output Speed (39.012).

Parameter | 31.015 AMC Auto Resolution Enable
--- | ---
Short description |
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

When AMC Auto Resolution Enable (31.015) = 0 the Advanced Motion Controller works in the resolution of the user units. If the output ratio (AMC Output User Units Ratio Numerator (31.008) / AMC Output User Units Ratio Denominator (31.009)) > 1 the resolution of the user units is lower than the resolution of the normalised position of the motor feedback device. For example, if the slave moves 100mm for every revolution of the motor and the motor normalised position has 16 position bits per revolution.

AMC Output User Units Ratio Numerator (31.008) / AMC Output User Units Ratio Denominator (31.009) = 65536 / 100

Speed resolution (0.01 User units / ms) = 0.01 x 60,000 / 100 = 6 rpm

To improve the speed resolution the user unit resolution could be increased from mm to μm. In this condition the output ratio will be less than unity and the resolution of the Advanced Motion Controller is limited by the resolution of the normalised position (0.0091 rpm).

Alternately, when AMC Auto Resolution Enable (31.015) = 1 the resolution of the internal units used by the Advanced Motion Controller is automatically increased by an internal scaling factor (AMC Auto Resolution Scaling (31.016)) which is the largest value (power of two) that maintains the output ratio at or above unity. This ensures that the maximum position reference (AMC Position Reference (34.003)) is greater than or equal to the number of normalised turns or poles of the motor feedback device and the internal speed resolution is never less than half the resolution of the normalised units. Note that the maximum value for AMC Auto Resolution Scaling (31.016) is the minimum of 231-1/AMC Master User Units Ratio Numerator (31.004), 231-1/AMC Slave User Units Ratio Numerator (31.006) and 231-1/AMC Output User Units Ratio Denominator (31.009). When this mode is used the internal resolution is increased but all of the user parameters are defined in user units, i.e. mm.

If this mode is enable in the example above (output ratio >> 1) the internal resolution can be increased as shown below.

AMC Output User Units Ratio Numerator (31.008) / (AMC Auto Resolution Scaling (31.016) x AMC Output User Units Ratio Denominator (31.009)) >= 1

AMC Auto Resolution Scaling (31.016) = 512 (largest power of 2 that satisfies the above requirements, i.e. output ratio >= 1)

Speed resolution (0.01 User units / ms) = 0.01 x 60,000 / (100 x 512) = 0.0117 rpm

If the output ratio is less than or equal to unity the resolution of the user units is limited by the resolution of the normalised units and AMC Auto Resolution Scaling (31.016) is set to unity.

Parameter | 31.016 AMC Auto Resolution Scaling
--- | ---
Short description |
Mode | RFC‑A
Minimum | 1 | Maximum | 2147483647
Default |  | Units |
Type | 32 Bit Volatile | Update Rate | Background write
Display Format | Standard | Decimal Places | 0
Coding | RO, ND, NC, PT

See AMC Auto Resolution Enable (31.015).