Delta RMC151 - Manual (Page 916)

RMC70/150 and RMCTools User Manual
Changing this Parameter
Because this parameter affects motion, the axis must be disabled or in Direct Output
before writing to this parameter. The Enabled and Direct Output Status Bits indicate these
states of the axis. When changing this parameter from RMCTools, the software will
automatically do this for you. This may cause a halt on the axis, which is expected.
9.2.2.2.11. Count Unwind
Type: Axis Parameter Register
RMC70 Address: %MDn.13, where n = 12 + the axis number
RMC150 Address: %MDn.13, where n = 24 + the axis number
System Tag: _Axis[n].CntUnwind, where n is the axis number
How to Find: Axes Parameters Pane, Setup tab: Primary Control Setup
Data Type: DINT
Units: pu
Range: > 0
Default Value: 1024
Description
This parameter is used on rotary position axes together with the Position Unwind, Position
Offset and Count Offset parameters to convert the transducer feedback Counts to an
Actual Position.
The Count Unwind parameter defines the range of feedback Counts that maps to the
Position Unwind. As the encoder rotates through the range of counts de fined by the
Count Unwind, the Actual Position will go through the entire range of numbers specified
by the Position Unwind.
For axes configured as Rotary Absolute, the Count Unwind parameter must be a power of
2, such as 1024, 8192, etc.
Example:
Consider an SSI Rotary Absolute encoder with 8192 counts per revolution. The user
wants to set it up so that it goes from 0 to 360 on one revolution. To do this, the Count
Unwind must be set to 8192, and the Position Unwind must be set to 360.
Valid Range
The valid range of the Count Unwind parameter is limited for certain feedback types.
• SSI Feedback on Absolute Rotary Axes
The Count Unwind parameter must be less than or equal to 2 N , where N is the SSI
Data Bits. For example, for a 13-bit SSI encoder, the SSI Data Bits would be set to 13,
and the maximum Count Unwind value would be 2 13 , which is 8192.
• Resolver Feedback on Absolute Rotary Axes
The maximum value of the Count Unwind parameter for resolver feedback is 65536.
Changing this Parameter
Because this parameter affects motion, the axis must be disabled or in Direct Output
before writing to this parameter. The Enabled and Direct Output Status Bits indicate these
states of the axis. When changing this parameter from RMCTools, the software will
automatically do this for you. This may cause a halt on the axis, which is expected.
9.2.2.2.12. Count Offset
896 Delta Computer Systems, Inc.