Baldor MN1940 - Manual (Page 20)

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4-4 Input / Output MN1940
4.3 Logic inputs
The DSM has three optically isolated logic inputs. These inputs are isolated to minimize or
eliminate electrical noise coupled onto the drive control signals, and are over-voltage
protected. The inputs may be configured as either sinking inputs or sourcing inputs (model
dependent, see section 4.3.3), with the Optocoupler Reference (white) lead as the reference.
This allows the DSM to be interfaced to a variety of controllers.
DSM
Optocoupler
reference
Step clock
input
Direction
input
Enable input
HCPL0630
PS2701-1
750R
HCPL0630
470R
470R
Figure 8 - Opto-isolated digital input circuit (sinking only)
4.3.1 Logic input descriptions
4.3.1.1 Step clock (orange flying lead)
The step clock input is where the motion clock from the control circuitry will be connected. The
motor will advance one microstep in the plus or minus direction (based upon the state of the
direction input) on the step clock edge that causes the opto-isolator to be active. The size of
this increment or decrement will depend on the microstep resolution setting. The maximum
frequency on the step clock input is 2.0 MHz, with a minimum pulse width of 400 ns.
4.3.1.2 Direction (blue flying lead)
The direction input controls the CW/CCW direction of the motor. A logic high (default,
unconnected) will cause the motor to rotate in the CW direction (seen while looking at the face
of the motor). A logic low on the input will cause the motor to rotate in the CCW direction. This
input is synchronized to the positive going edge of the step clock input. The direction input
may be connected by means of a switch.
4.3.1.3 Enable (brown flying lead)
This input can be used to enable or disable the driver output circuitry. A logic high (when the
enable switch is open, see Figures 9 and 10), causes the driver outputs to be enabled and
step clock pulses will cause the motor to advance. A logic low (when the input switch is