Baldor iMN1921 installation manual Stepper axes 0-3 logic outputs

4.3.2 Stepper axes 0-3 logic outputs

DGND

STEP3

DGND

STEP2

DGND

STEP1

DGND

STEP0

DIR3

BOOST3

DIR2

BOOST2

DIR1

BOOST1

DIR0

BOOST0

J3

NextMove ST
	ULN2003
Step	STEP0
	74AHCT244
Output
GND	DGND

Figure 9 - Stepper output pin header J3, and output circuit (STEP0 shown)

To allow external stepper amplifiers to be used, all of the stepper output signals from the NextMove ST control card are output on a 16-pin header, J3, mounted on the card. There are four sets of stepper motor control outputs, operating in the range 10Hz to 1MHz. The step (pulse), direction and boost signals from the NextMove ST control card are divided into two groups, each group driven by an ULN2003 open collector Darlington output device.

Each ULN2003 has a maximum power dissipation of 900mW at 25°C. The total combined output requirements for the group DIR0 - DIR2 and STEP0 - STEP2 must not exceed this limit. The total combined output requirements of the group DIR3, STEP3 and BOOST0 - BOOST3 must not exceed this limit. The maximum current limit for any individual output in a group is 400mA if only one output is in use, reducing to 50mA if all outputs in the group are in use. These limits are for a 100% duty cycle.

It is recommended to use separate shielded cables for the step outputs. The shield should be connected at one end only.

The STEP2, DIR2 and BOOST2 outputs are also duplicated on the MISC connector.

4-8 Input / Output MN1921