Installation guide

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Keyword Reference Guide

MN1270 02.2002 61

Dot Parameters:

Channel - DAC Channel

Attributes:

Controller Read Write Command Multi-

Axis

Scaled Default Range

NextMove

 

0 0 - 4

MintDrive

 

0 0, 1, 2, 3, or 5

Description:

Certain system parameters, can be monitored externally by outputting the value through a DAC channel.

The

DACMONITORAXIS keyword specifies which axis is to be used for monitoring through the DAC

channel. The

DACMONITORGAIN keyword can be used to scale the size of the output voltage.

The possible parameters to monitor are:

Mode Meaning NM Mint

Drive

0 Turns DAC monitoring off

 

1 The axis measured velocity is output in counts / second

 

2 The axis demand velocity is output in counts / second

 

3 The axis following error is output in counts

 

4 The free spaces in the axis move buffer is output

 

5 The axis demanded DAC output



The DAC can output values in the range ±2047 which equates to ±10V.

Any axis can be monitored and multiple axis parameters can be monitored through the use of multiple

DAC channels. Note that this keyword is channel dependant and not axis dependent. The DAC

channels on a NextMove expansion board can be used if one is present.

The axis owning the DAC channel to be used for monitoring must be configured as off (see

CONFIG).

Whilst DAC monitoring is turned on, a DAC value set with the DAC keyword will be overwritten.

Example:

CONFIG.3 = _cfOFF : REM Turn axis 3 off so its DAC can be used

DACMONITORAXIS.3 = 0 : REM Monitor axis 0 on DAC channel 3

DACMONITORMODE.3 = 1 : REM Send axis 0 velocity to the DAC.

DACMONITORGAIN.3 = 10 : REM Scale output by ten.

For example, if the DAC voltage is -5V, this equates to -1024 DAC counts. If the DAC is monitoring

measured velocity with a monitor gain of 10.0, then the axis has a velocity of 102.4 counts / second.

Controller Specifics:

NextMove BX and PCI use a 14 bit DAC which has a of ±8191 counts. In the example above, a DAC

voltage of -5V equates to -4095 DAC counts. With a gain of 10 this would indicate a velocity of 409.5

counts / second.