Delta RMC101 User Manual download pdf (Page 621)

100

101

SSI 6.6

Transducer Interface Modules 6-77

For general scaling information, see the Scaling Overview topic.

Because the RMC uses 16-bit positions, positions must all fit within a range of 65,536 position

units. Because position units are user definable, this range does not limit most applications. See

the section below on defining position units.

For SSI axes, the Offset parameter is used with the Scale parameter to define the position range.

If the Scale parameter is negative, then the position range extends from the Offset value minus

65535 up to the Offset value. If the Scale parameter is non-negative, then the position range

extends from the Offset value up to the Offset value plus 65535. The following chart summarizes

this concept:

Scale

Min. Position

Max. Position

< 0

Offset - 65535

Offset

³ 0

Offset

Offset + 65535

However, because the Offset is also used to convert transducer counts to position units, it cannot

be set independently.

Translating to Position Units

Before the translation from counts to position units begins, the Count Offset SSI configuration

setting is applied to the counts. This means that the value of the Count Offset is subtracted from

the Counts before they are displayed or processed in any way. For a full discussion on the use of

the Count Offset setting, see SSI Configuration.

The Scale, Offset, and the Prescale Divisor bits of the Configuration word parameters are used to

define position units as a function of transducer counts. Below is shown an example SSI and the

effect of the Scale, Offset, Extend and Retract Limits:

The following formula summarizes the translation from transducer counts to Actual Position units:

As described above, the Counts field has already had the Count Offset configuration setting

subtracted from it before using this formula. If the Actual Position overflows the valid 16-bit

position range, as described above, the Position Overflow bit will turn on, forcing the axis to halt.

Notice that the Scale can hold values from -32768 to 32768, but 16-bit signed numbers are

limited to -32768 to 32767. Therefore, enter a scale of 32768 as 0; the RMC will interpret it as

32768.

There are two main ways to calculate the Scale, Offset, and Prescale Divisor bits. Each method is

described below. Notice that both have automatic Calibration Utilities built into RMCWin. It is

1 2 ... 616 617 618 619 620 621 622 623 624 625 626 ... 950 951

Comments to this Manuals

No comments

Delta RMC101 User Manual Page 621

Comments to this Manuals

Related products and manuals for Sensors Delta RMC101