Download Stepper Motor Driver BCMSSMD1

Stepper Motor Driver BCMSSMD1
The stepper motor driver is based around a commercial stepper motor drive type SD2
manufactured by Digiplan.
A clock that dictates the motor rotation speed is available internally when the biased
toggle switch is in the INT CLOCK position or externally when this switch is in the EXT
CLOCK position. The internal clock rate and hence motor speed can be adjusted via the
INT CLOCK RATE control. The internal clock rate is intentionally set at a slow rate
(aprrox 40 -1000Hz) so as to permit fine control of the stepper motor in the INT CLOCK
position.
Motor Power Dissipation
If the clock is stopped (INT or EXT) current will still be flowing in the motor coils which
can lead to heat dissipation that may damage the motor and the controller. The motor
can be disabled, when no current is drawn in the windings, by use of the
ENABLE/DISABLE toggle switch. It is recommended that if the motor is stopped for long
periods the DISABLE position is selected so as to reduce power dissipation in the motor
and controller
External clock input
The SD2 clock is typically 0V low 12V high. In order to accommodate TTL clock levels
from a PC I/O port or similar device, a level shifter has been incorporated in the EXT
CLOCK input line. TTL level signals need only be capable of sourcing 100uA in the high
state when applied to the EXT CLOCK input. If higher voltage clock levels are applied to
the EXT CLOCK input no damage will result but the internal clamp of the 5V1 zener diode
in the level shifter will take effect and the input current at 15V will typically be 1mA.
The step occurs on the falling edge of the external clock and the external clock should
remain high for at least 10uS prior to this falling edge.
400 steps are required for one rotation.
With the load of the viscometer attached to the motor the maximum clock frequency is
1.2 KHz for guaranteed driving of the motor. This equates to 3 RPS (1200/400).
Front Panel
DISABLE/ENABLE toggle switch
ENABLE
Motor turns under control of stepper driver
DISABLE
Motor free to rotate-no current in motor coils
DIRECTION/REVERSE toggle switch
DIRECTION
Motor rotates in direction dictated by coil connections
REVERSE
Motor rotates in opposite direction to above
EXT CLOCK/INT CLOCK biased toggle switch
EXT CLOCK
The biased position of the switch when motor speed is controlled by
pulses at the EXTNERAL CLOCK input
INT CLOCK
User held (self return) position when motor speed controlled by
internal SD2 clock
INT CLOCK RATE multi-turn potentiometer
Varies the rate of the internal SD2 clock
MAIN ON
Mains power switch and indicator
REAR PANEL
DRIVE TO MOTOR 5 pin DIN socket
Output connection to stepper motor
1
Motor Phase B-
4
Motor Phase B+
2
No connection
5
Motor Phase A-
3
Motor Phase A+
EXT CLOCK IN
Input for external clock drive