Control Techniques Nidec SI-EtherCAT User Manual page 78

7.3.17 Basic position control
Basic position control is supported on the Unidrive M70x and Digitax HD in RFC-A and RFC-S
modes. The position control described here is used under the interpolated position mode of
operation. Table 7-36 lists the objects that are supported:
Table 7-36 Basic position control supported objects
Index
0x6062
0x6065
0x6067
0x6068
0x60F4
0x60FB
7.3.18 0x6062 Position_demand_value
This read only object is used to provide the currently demanded position value. The value is given
in user defined position units.
Table 7-37 Position_demand_value
0x6062 Position_demand_value
Access: RO
Default: N/A
PDO Mappable: TxPDO
Motion Profiles: CSP, IP, PP
Description: Used to provide the currently demanded position value.
7.3.19 0x6064 Position_actual_value
This read only object provides the actual value of the position feedback device. The value is given
in internal units.
Table 7-38 Position_actual_value
0x6064 Position_actual_value
Access: RO
Default: N/A
PDO Mappable: TxPDO
Motion Profiles: ALL (when position feedback is available)
Description: This read only object provides the actual value of the position in User-defined position units.
Although Actual position is an absolute value, there are various conditions that the user must be
aware of. When setting gear ratios that are not 1:1 and the encoder count rolls over, EtherCAT
module attempts to keep the position contiguous at the point of rollover; BUT this means keeping
track of the rollovers so that a suitable offset can be added to the raw encoder count to keep
position contiguous. This cannot be maintained after the following events:
• Drive Power cycle
• Drive reset
• EtherCAT module reset
• Change of CiA402 mode to VL Velocity or CST
• EtherCAT communications state moving out of Operational state
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position_demand_value
following_error_window
position_window
Position window time
following_error_actual_value
position_control_parameter_set
32 32
Range: -2 to 2 -1
31 31
Range: -2 to 2
Name
Size: 4 bytes
Type: Signed integer / DINT
Update rate: Every Network Cycle period
Size: 4 bytes
Type: Signed integer / DINT
Update rate: Every Network Cycle period
SI-EtherCAT User Guide
Unit: User units
Unit: N/A