Intelligent Motion Systems DSP-402 manual Functional Description

Functional Description

There are two different ways to apply target_positions to a drive, are supported by this device profile.

1.Set of set-points:

After reaching the target_position the drive unit immediately processes the next target_position which results in a move where the velocity of the drive normally is not reduced to zero after achieving a set-point.

2.Single set-point:

After reaching the target_position the drive unit signals this status to a host computer and then receives a new set- point. After reaching a target_position the velocity normally is reduced to zero before starting a move to the next set-point.

The two modes are controlled by the timing of the bits new_set-pointand change_set_immediately in the controlword and set-point_acknowledgein the statusword.

These bits allow to set up a request-response mechanism in order to prepare a set of set-points while another set still is pro- cessed in the drive unit. This minimizes reaction times within a control program on a host computer.

data

Bit 4: new_set-point

ControlWord

(6040h)

Bit 5: change_set_immediately

StatusWord	Bit 12: set-point_acknowledge
(6041h)

2 4

6

0 = Single Set-Point 1 = Set of Set-points

1

3 5

1Single Set-Point is Expected by MDrivePlus

2Host Signals “Data is Valid” new_set-point = 1

3MDrivePlus responds by setting Bit 12, set-point_acknowledge = 1

4Once Data is Validated, Host may release new_set-point

5MDrivePlus responds by setting Bit 12, set-point_acknowledge = 0 MDrivePlus is ready to accept new data

6Indicates state Change of change_set_immediately to 1

Figure 6.2: Set-Point Transmission from Host Computer

Figure 6.2, Figure 6.3 and Figure 6.4 illustrate the difference between the “set of set-points” mode and the “single set-point” mode. The initial status of the bit change_set_immediately in the controlword determines which mode is used. Trapezoidal moves are used as this is the only motion_profile_type the MDrivePlus CANopen supports.

If the bit change_set_immediately is “0” (shaded area in Figure 3.2) a single set-point is expected by the drive . After data is applied to the drive, a host signals that the data is valid by changing the bit new_setpoint to “1” in the controlword . The drive responds with set-point_acknowledgeset to “1” in the statusword  after it recognized and buffered the new valid data. Now the host may release new_setpoint  and afterwards the drive signals with set-point_acknowledgeequal “0” its ability to accept new data again . In Figure 3.3 this mechanism results in a velocity of zero after ramping down in order to reach a target_position X1.at T1. After signalling to the host, that the set-point is reached like described above, the next target_posi- tion X2 is processed at T2 and reached at T3.

36 MDrivePlus CANopen R020507