Quadrature with Analog Output Overview

The QUAD module is one of two RMC modules with an interface for quadrature encoder feedback. This module provides analog drive output, while the STEP interface module provides stepper drive output. Together, these modules allow the RMC100 series motion controllers to control a wide range of motors and linear actuators with quadrature encoder feedback. For details on the STEP module, see Quadrature with Stepper Output Overview.

Features

Two Complete Axes per Module. Each includes the following:

Quadrature Encoder Interface:

4,000,000 counts/second
A and B Inputs
Index Input with High-speed 125hs Position Latch

Drive Amplifier Interface:

Isolated ±10V, 12-bit Analog Drive Output
Amplifier Enable Output
Amplifier Fault Input

Additional Inputs:

Extend (CW) Travel Limit Input
Retract (CCW) Travel Limit Input
Home Input with High-speed 50µs Position Latch

Status LED

Digital Noise Filters on All Inputs
All Discrete Inputs are Isolated
Use with Servo Drives in Velocity or Torque/Force Modes

Quadrature Encoder Inputs

The A and B signals from the encoder are decoded to generate a positive or negative count; the count is then used to monitor the axis position. Each signal from the encoder is received into a differential line receiver for compatibility with differential line driver encoders. The negative input is biased so some encoders with open collector or TTL outputs can also be used, however such encoders should only be used in lab environments with very little electrical noise and short wire runs.

Index (Z) Input

The index input is normally active for one count of each quadrature encoder revolution. It is used to qualify or narrow the effective width of the home input to make the homing more repeatable; see Homing a Quadrature Axis for details. The user may change the active state of this input by changing the Home Active State bit in the axis’s Config word.

Home (H) Input

This input may be used in homing the system; see Homing a Quadrature Axis for details. This input will be connected to a normally-off proximity switch. The user may change the active state of this input by changing the Home Active State bit in the axis’s Config word.

Amplifier Enable Output

This output to the drive amplifier allows the RMC to turn off the amplifier using the Amp Enable/Disable command. The enable output (labeled ENABLE + and -) is a solid state relay that is closed when enabled or active.

Amplifier Fault Input

FAULT + and - is an input from the drive amplifier or some other source that tells the RMC it no longer has control and should output the null drive, usually zero volts, and go into open loop mode. The user can select the active state of this input by the Fault Active State bit in the axis’s Config word; by default the RMC is set-up to fault when current stops flowing through the input. This way the axis will fault on loss of control power. Bit 15 of the Status word is set if a Fault or Encoder error has occurred. The Auto Stop parameter determines how the axis will stop when a fault occurs.

Note: The axis will soft stop when this error occurs if no auto stop bits are selected.

Extend and Retract Travel Limit Inputs

The Extend Limit (CW) and Retract Limit (CCW) switch inputs tell the RMC that a travel limit has been reached and the axis should halt. By default the limit switches are considered inactive when enough current is flowing through the RMC inputs. This way the limit switches will look active to the RMC if control power is lost. The user may change the active state by setting the Limit Switch Active State bit in the axis’s Config word.

Note: There is only one bit in the Config word for both limit switches so both limit switches must have the same active state.

If a limit switch is not used it should be wired in the inactive state or the Limit Switch Active State bit must be configured to disable the inputs. The Auto Stop bits must be set to automatically stop the axis.