Flexible Encoder TDC Offset

This MotoHawk™ block sets a encoder source TDC offset in 1/16 degrees before TDC for the referenced encoder source.

Block ID

Set TDC offset

Library

MotoHawk_flexenc_lib

Description

Use the input to set the encoder TDC offset, which is required to translate encoder TDC#1 to mechanical TDC#1. It has a fixed point representation with units of 1/16 degrees before TDC#1.

Encoder TDC#1 always refers to tooth#0 of the flexible encoder pattern being used by the referenced source. It is not related to the key, though often the two happen to align (such as in missing tooth type patterns). The example illustrates.

Typically this is fed by a Calibration block, so that the mechanical to electrical TDC offset can be tuned.

This block can be used to change the offset at run-time, for example, to add 360 degrees to change the CAM phase.

This block is synonymous to the Encoder TDC Offset except it references the absolute source that it is to affect and can thus be used in a multiple source system.

A legacy encoder system is different than the Flexible Encoder implementation and as such encoder TDC offset should be re-considered when porting from a legacy encoder system to a Flexible Encoder System.

Block Parameters

Parameter Field Values Comments/Description
Reference Source Name Alpha-numeric text, quote enclosed The name of the Flexible Encoder Absolute Source block that is to have its offset set.

Example

The rising edge of the yellow pulse is engine TDC#1 (0degCA). Created the scope plots using a basic PSP with a stop timing of 0deg that is running using a 6P1 encoder as its absolute source. The tooth after the extra tooth is tooth#0 of the pattern.

TDC Offset of 0 with 6P1. The encoder offset is set to 0. Note that the rising edge aligns with the tooth after the additional tooth.

TDC Offset of 120 with 6P1. The encoder offset is set to 120. Note that the rising edge aligns with the tooth before the additional tooth (left of TDC0).

TDC Offset of 600 with 6P1. The encoder offset is set to -120(==600). The rising edge is to the right.