Installation guide

Mint™ v4 Advanced Programming Guide

70 MN1270 02.2002

Format:

ENCODERZLATCH.channel = <expression>

v = ENCODERZLATCH.channel

Dot Parameters:

Channel – Encoder Channel Number.

Attributes:

Controller Read Write Command Multi-

Axis

Scaled Default Range

All



0 or 1

Description:

The encoder ASIC which is fitted to the NextMove PCI, MintDrive and ServoNode controllers will

latch the edge of an encoder Z pulse within hardware. Generally the width of an encoder Z pulse is too

narrow to poll for reliably using software alone. When an encoders Z pulse is seen the occurrence of

this is latched within the hardware. It is this latched value that the

ENCODERZLATCH keyword reads.

The action of reading this register clears it, hence when using the

ENCODERZLATCH keyword to search

for a Z pulse the value of

ENCODERZLATCH must be read first to ensure that any existing hardware latch

is cleared.

Example:

a = ENCODERZLATCH.0 : REM read and clear the encoder z latch

REPEAT : REM wait until the z pulse is seen

REM do nothing

UNTIL ENCODERZLATCH.0 = 1

ENCODER.0 = 0 : REM zero the encoder position

The above code example will firstly clear the encoder z latch, then wait until another z pulse occurs, at

which point the position of the encoder is set to zero.