---
name: "eoffset_per_angle"
section: "9"
platform: "linux"
package: "linuxcnc-uspace"
version: "1:2.9.4-2+deb13u1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/eoffset_per_angle"
---

# eoffset\_per\_angle(9)

Compute External Offset Per Angle

## NAME

eoffset\_per\_angle - Compute External Offset Per Angle

## SYNOPSIS

**loadrt eoffset\_per\_angle \[count=*N*\|names=*name1*\[,*name2...*\]\]**

## DESCRIPTION

An offset is computed (from one of several functions) based on an input angle in degrees.  The angle could be a rotary coordinate value or a spindle angle.

The computed offset is represented as an s32 **kcounts** output pin that is a compatible input to external offset pins like **axis.L.eoffset-counts** where **L** is the coordinate letter.  Scaling of the s32 **kcounts** is controlled by the input (**k**) -- its reciprocal value is presented on an output pin (**kreciprocal**) for connection to **axis.L.eoffset-scale**. The default value for **k** should be suitable for most uses.

The built-in functions use pins **fmult** and **rfraction** to control the output frequency (or number of polygon sides) and amplitude respectively.  The  **rfraction** pin controls the offset amplitude as a fraction of the **radius-ref** pin.

One of the four built-in functions is specified by the **fnum** pin:\
   **0**: f0 inside  polygon  (requires **fmult** == nsides \>= 3)\
   **1**: f1 outside polygon  (requires **fmult** == nsides \>= 3)\
   **2**: f2 sinusoid\
   **3**: f3 square wave

Unsupported **fnum** values default to use function f0.

## FUNCTIONS

- **eoffset-per-angle.***N* (requires a floating-point thread)

  ## PINS

- **eoffset-per-angle.*N*.active bit in (default: *0*)**

  From: motion.eoffset-active

- **eoffset-per-angle.*N*.is-on bit in (default: *0*)**

  From: halui.machine.is-on

- **eoffset-per-angle.*N*.enable-in bit in (default: *0*)**

  Enable Input

- **eoffset-per-angle.*N*.radius-ref float in (default: *1*)**

  Radius reference (see notes)

- **eoffset-per-angle.*N*.angle float in (default: *0*)**

  Input angle (in degrees)

- **eoffset-per-angle.*N*.start-angle float in (default: *0*)**

  Start angle (in degrees)

- **eoffset-per-angle.*N*.fnum s32 in (default: *0*)**

  Function selector (default 0)

- **eoffset-per-angle.*N*.rfraction float in (default: *0.1*)**

  Offset amplitude (+/- fraction of radius\_ref)

- **eoffset-per-angle.*N*.fmult float in (default: *6*)**

  Offset frequency multiplier

- **eoffset-per-angle.*N*.k u32 in (default: *10000*)**

  Scaling Factor (if 0, use 10000)

- **eoffset-per-angle.*N*.is-off bit out**

  invert is\_on (for convenience)

- **eoffset-per-angle.*N*.enable-out bit out**

  To: axis.L.eoffset-enable

- **eoffset-per-angle.*N*.clear bit out**

  To: axis.L.eoffset-clear

- **eoffset-per-angle.*N*.kcounts s32 out**

  To: axis.L.eoffset-counts

- **eoffset-per-angle.*N*.kreciprocal float out**

  To: axis.L.eoffset-scale (1/k)

- **eoffset-per-angle.*N*.eoffset-dbg float out**

  offset (debug pin--use kcounts & kreciprocal)

- **eoffset-per-angle.*N*.state-dbg u32 out**

  state  (debug pin)

## EXAMPLES

An example simulation configuration is provided at: **configs/sim/axis/external\_offsets/opa.ini**.  A simulated XZC machine uses the **C** coordinate angle to offset the transverse **X** coordinate according to the selected **fnum** function.

## NOTES

**radius-ref**: The computed offsets are based on the **radius-ref** pin value.  This pin may be set to a constant radius value or controlled by a user interface or by g code program (using **M68** and a **motion.analog-out-NN pin for instance).**

**Stopping**: When the **enable-in** pin is deasserted, the offset is returned to zero respecting the allocated acceleration and velocity limits.  The allocations for coordinate **L** are typically controlled by an ini file setting: **\[AXIS\_L\]OFFSET\_AV\_RATIO**.

If unsupported parameters are supplied to a function (for instance a polygon with fewer than three sides), the current offset will be returned to zero (respecting velocity and acceleration constraints).  After correcting the offending parameter, the **enable-in** pin must be toggled to resume offset computations.

## AUTHOR

Dewey Garrett

## LICENSE

GPL