Table of contents |

# Analog I/O Status Screen

(Click on above image to jump to relative topic)

The Analog I/O Status Screen displays various analog measurements and commands including:

- Measured +/10 V ADC inputs
- Measured current flow per axis
- Commanded +/10 V DAC outputs
- Commanded 0-4V DAC outputs
- Commanded PWM power amp settings
- Commanded Destinations of each axis
- Measured Position of each axis
- Status and Mode of each axis

KMotion has a number of 12-bit ADC and DAC channels that may be used either as servo channel inputs and outputs or as general purpose data acquisition and command signals.

## ADC's

KMotion's ADC channels may also be read by a host computer via the Console Script Command: ADCn, or by a on-board C program via the ADC(n) macro. These commands return ADC counts in the range of -2048 to 2047 counts.

The first four of KMotion's eight on-board ADC channels are general purpose +/- 10V inputs. Note that in order for these to operate properly, the on-board 5V to +/- 15V power generation must be enabled. The input buffers are inverting such that nominally +10V corresponds to -2048 ADC counts, 0 V corresponds to 0 ADC counts and -10V corresponds to +2047 ADC counts. See the input circuit here. Both the ADCs and DACs are designed to have slightly larger (nominally 2%) than +/- 10V range to account for component tolerance errors. In this way the ranges may always be scaled and offset to provide exact +/-10 V ranges.

Certain of KMotion's servo input modes allow ADC inputs as position information instead of digital encoder inputs. Such as ADC Input mode and Resolver Input modes. The Resolver servo input mode requires two ADC channels configured as sine and cosine signals. There are insufficient ADC channels for more than two axis to be configured as Resolver input mode. When configuring an axis for a mode utilizing an ADC input the corresponding InputChannel(s) (0 and 1) for the axis must be set appropriately. Additionally, the corresponding Input Gains and Offsets for the axis may be used to correct for scale and offsets in either the ADC channels or the sensor itself.

Of KMotion's eight on-board ADC channels, four of the channels are dedicated to measuring current flow through each axis of the on-board power amplifiers. ADC Channels 4-7 normally corresponding to axis 0-3 (if default output channel mapping is used). Since each axis consists of two full-bridge power amplifiers, the measured current per axis is the sum of both full bridges. This provides a convenient means to determine abnormal conditions such as stalled motors or open motor coils. This feature is designed to make an approximate measurement of axis current, not a precise measurement of axis current.

The range of current measurement is fixed at nominally 0 - 4.85 Amps. Since each of KMotion's full bridge power amplifiers are rated for 3 Amps continuous (per full bridge) and are normally utilized to drive a 4 phase motor (such as a stepper motor), a worst case current per axis occurs when both coils are conducting 0.707 of 3 Amps or 4.24 amps. The 4.85 Amp range provides some margin beyond this. An zero current corresponds to an ADC reading in counts of -2048 and 4.85Amps corresponds to an reading of +2047 counts.

Small bar charts on the screen also provide an indication of current in each axis, see below. The graph displays a green bar from 0 to 100% full which corresponds to 0 to 3A of current. Currents higher than 3A show a full red bar which may indicate an over current situation if more than 3A is flowing in any one of the two full bridge circuits.

## DAC's

KMotion's DAC channels may be set by a host computer via the Console Script Command: DACn=x, or by a on-board C program via the DAC(n,x) macro. These commands set the DAC counts in the range of -2048 to 2047 counts.

The first four of KMotion's eight on-board DAC channels are general purpose +/- 10V outputs. Note that in order for these to operate properly, the on-board 5V to +/- 15V power generation must be enabled. The output buffers are inverting such that nominally +10V corresponds to -2048 ADC counts, 0 V corresponds to 0 ADC counts and -10V corresponds to +2047 ADC counts (similar to the ADC readings). See the output circuit here. Both the ADCs and DACs are designed to have slightly larger (nominally 2%) than +/- 10V range to account for component tolerance errors. In this way the ranges may always be scaled and offset to provide exact +/-10 V ranges.

The next four of KMotion's eight on-board DAC channels are general purpose 0 - 4V outputs. These outputs do not require the on-board 5V to +/- 15V power generation to be enabled. 0 V corresponds to -2048 ADC counts and +4V corresponds to +2047 ADC counts.

## PWM's

The state of KMotion's eight PWM (Pulse Width Modulators) are displayed in the top right area of the status screen. The PWM's are connected to on-board Full Bridge Drivers to allow direct control of various motors or loads. See the description of KMotion's Power Amplifiers and PWM's for details. The PWM's may operate independently to drive a full bridge driver, or they may function as a pair of PWM's connected to a pair of Full Bridge drivers to drive a 3 phase load. The default and recommended PWM assignment is to have:

Axis 0 configured to utilize PWM 0 and 1

Axis 1 configured to utilize PWM 2 and 3

Axis 2 configured to utilize PWM 4 and 5

Axis 3 configured to utilize PWM 6 and 7

However the PWMs may be reassigned by changing the OutputChan0 and OutputChan1 parameters for an axis. Only consecutive even and odd PWMS (0/1, 2/3, 4/5, or 6/7) may be paired to drive a 3 phase load.

Therefore, there are three possible modes for each PWM channels:

- Normal Independent
- Recirculating Independent
- 3 Phase - paired

If a PWM channel is operating in Normal mode, the PWM channel status will show the value in counts (-255 ... +255) and the percent of full scale.

If a PWM channel is operating in Recirculating mode, the PWM channel status will show the value in counts (-511 ... +511), followed by an "R", and the percent of full scale.

If a pair of PWM channels is operating in 3 Phase mode, the PWM channel status will show the value in counts (-230 ... 230) after the first PWM channel and the phase angle in degrees after second PWM channel.

The example status below shows PWM channels 0 and 1 operating in 3 phase mode, PWM channels 2-5 operating in Normal mode, and PWM channels 6 and 7 operating in Recirculating mode.

## Dest

This section of status displays the currently commanded destination for each axis. The Destination is the theoretically desired position for the axis. If a move is in progress, this is the current point along the desired trajectory of the motion. The units are in position units for the axis.

## Pos

This section of status displays the currently measured position for each axis. Depending on the input mode for the axis, this position may represent an encoder position, a resolver position, or an absolute position based on an ADC reading. An axis operating as an open loop microstepper mode may have no position sensor at all. In this case the position value is meaningless and ignored.

## Enable

Displays whether an axis is enabled or not. Clicking on the Enabled checkbox will enable the axis if disabled or disable the axis if enabled.

## Modes

Displays the currently configured input and output modes for each axis. The input mode determines what technique is used to determine the axis's measured position. The output mode determines how the axis's output should be driven.

Valid input modes are:

- Encoder
- ADC
- Resolver
- User Input

Valid output modes are:

- Microstep
- DC Servo
- 3PH Servo
- 4PH Servo
- DAC Servo

## Done

Displays whether an axis operating as an independent axis (not a coordinated motion axis) has completed its last trajectory.