©
National Instruments Corporation
17
MID-7604/7602 Power Drive User Guide
Warning
The stepper motor connectors on this drive are energized when the unit is
powered on. Disconnect the MID-7604/7602 unit from the power outlet
before
connecting
wires to or disconnecting wires from the stepper connectors. Strip back the insulation of
the stepper wires to the stepper connectors no more than 7 mm.
Failure to do so could
result in electric shock leading to serious bodily injury or death.
Use shielded, 20 AWG wire or larger for the motor power cable.
If available, you should connect a case ground wire to pin 3
(Ground/Shield) to avoid ground loops and signal noise problems.
Case ground connects to the motor housing, not to the motor power
terminals.
The MID-7604/7602 contains bipolar chopper drivers. You must wire the
stepper motors in a 4-wire configuration as shown in Figure 4. You must
isolate unused lead wires and leave them disconnected. Refer to the
section of this guide for additional
information on connecting 6- and 8-wire motors and on the alternate
half-coil configuration.
Caution
Never connect unused center taps or winding terminals to pin 3 (ground) or to
each other.
Encoder Terminal Blocks
For quadrature incremental encoder signals, each MID-7604/7602 axis has
a separate 8-position removable screw terminal block. Where applicable,
the MID-7604/7602 accepts two types of encoder signal inputs:
single-ended (TTL) or differential line driver. You can accommodate
open-collector output encoders by using 2.2 k
Ω
pullup resistors to
+5 VDC.
Figure 5 shows the typical encoder wiring pin assignment for single-ended
signal input.
Figure 5.
Typical Single-Ended Encoder Wiring Pin Assignment
1
2
3
4
5
6
7
8
Encoder A
Encoder B
Encoder Index
+5 V
Digital Ground
