Data Acquisition and
Control
Stepper Motor Control and
Drive Overview
The aim of this
document is to show you how Hytec’s Stepper Motor Control and Drive system
is put together, how it works and how it differs from similar systems.
The
system consists of two main parts. The controller is housed in an Industry
Pack, either on a VME64x carrier card (8002) or mounted inside a 9010 IOC
unit. Outside the VME64x crate or 9010, a standard SCSI-2 cable connects to
a separate rack-mounting enclosure housing the driver system.
Looking at each part in more detail:
The
CONTROLLER (Hytec 8601) has four independent channels of stepper
control; each has four outputs and eight inputs. The outputs are STEP,
DIRECTION and two Auxiliaries, which can be used, for example, to control
motor current. The inputs are three limit switches including HOME;
quadrature encoder signals(phase A, phase B and INDEX), drive system fault
plus two spares.
Each
channel of the controller features programmable START/STOP speed, HIGH speed
and RAMP RATE. Each has a 32-bit step register for the current move and a
32-bit accumulator, which follows all movements. Moves can be either fully
programmed, i.e. move the specified number of steps, or JOG, where the
channel steps until the control bit is reset. Soft stop and hard abort are
supported, along with stop on limit and stop at HOME. The accumulator can
count step pulses issued or pulses from an incremental encoder.
The
control bits for all channels are directly mapped into registers accessible
by the host. A COMMON START facility is also included so you always
have direct control over when a given channel or channels will start.
This
controller then connects to the outside of the system via a
‘straight-through’ transition card and then to the INTERFACE ELECTRONICS
mounted in the back of the driver system This performs basic signal
conditioning and buffering of all inputs and outputs of the controller card,
including RS422 level conversion for encoder signals if needed. It is fully
opto-isolated in both directions. This interface then connects to the driver
system motherboard directly and to auxiliary signals, such as encoders,
through 15-way Cannon connectors.
The
DRIVER (SMDS4) is a separate 3U high rack mounting unit. The driver
houses four drive cards and a common logic card. The unit can use UNIPOLAR
or L/R drive cards where the current limit is provided by external series
resistors or BIPOLAR drive cards, where current control is by pulse width
modulation. Both of these types are for use with standard four-phase hybrid
steppers with four, 6 or 8 leads in full or half-step mode. Phase current
can be up to 4 amps and is programmed by switches on each chopped drive
card. We also have drive cards for three-phase and five-phase motors
(Oriental Motor Company).
Any
mixture of drive cards can be accommodated.
For
standard power chopped-drive systems, the 24-volt PSU is integral. For
higher power L/R systems it is normally external.
HYTEC HOME PAGE
HYTEC Head
Office
Post : 5 Cradock Road, Reading, Berkshire, RG2 0JT, England.
Phone : +44 (0)118 9757770
Fax : +44 (0)118 9757566
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Copyright © 2007
[Hytec Electronics Ltd]. All rights reserved.
Information in this document is subject to change without notice.
Other products and companies referred to herein are trademarks or registered
trademarks of their respective companies or mark holders.
Our policy is one of continuous product development and the right is reserved
to supply equipment which may vary slightly from that described.
Last modified:
October 29, 2008
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