Features

This 4-axis position-control module has these features:

• Open-loop or closed-loop control

• Independent and coordinated axis control

• Position- and time-based control

• Accumulator push-out control

• Zero-scale/full-scale (offset & span) calibration for position inputs

• PID with anti-windup, bumpless parameter changes, setpoint weighting, and 

limited high-frequency derivative gain.

• Profile interpolation (linear or cubic spline) between setpoints

• Converging/diverging tooling (direct/reverse acting control)

• Three hold values per axis: manual position, purge, or die gap

• Independent profile scale and offset adjustments 

• Automatic parison weight adjustment

• Setpoint marking

Overview

The module performs its servo control task independently, but is dependent on the 

SLC processor for all of its configuration and run-time information. The processor 

may be also be used to supply process data or timing information over the 

backplane in certain situations (e.g. parison drop synchronization on continuous 

extrusion machines, or accumulator position in reciprocating screw machines).

The module uses a digital signal processor running a 

Proportional-Integral-Derivative (PID) algorithm to control four axes of motion. 

Four analog inputs and four analog outputs are used for process variables and 

signals, while four digital inputs and four digital outputs are used for start-of-drop 

synchronization and profile step synchronization signals, respectively. An excitation 

voltage is provided for use with linear potentiometers.

Communication with the SLC Processor

• shared memory

• control bit/status bit handshake

• micro processor

• PID control algorithm

• digital I/O

• analog I/O