Section 5: Motor Connections
Stepper motors have four, six, or eight wires; older motors may have five wires, but they will not be covered here.
Four-wire motors are the simplest to connect and offer no connection options. Simply connect one winding to the terminals labeled “Phase A” and “Phase /A” and connect the other winding to the terminals that say “Phase B” and “Phase /B”. If it is unknown which wires belong to which phase, simply use an ohmmeter and test which wires have continuity. The ones that have continuity will belong to the same phase; if the motor turns the wrong direction when connected just swap “Phase A” and “Phase /A”. A typical four-wire motor connection is illustrated in Figure 8.
Six-wire motors are the most common. There are two connection options: Full-winding and half-winding. A six-wire motor is just like a four-wire motor except there is a center tap on each of two windings, for a total of six wires. For a half-winding connection, the center tap and one of the end wires are used. This is illustrated in Figure 9.
For a full-winding connection as seen in Figure 10, the center tap is ignored and both end wires are used. The term “full-winding” is exactly equivalent to “series” connected while “half-winding” is virtually identical to “parallel” connected. The choice between the two is application dependent, which is discussed later; just remember to set the drive current to exactly half the motor’s rated unipolar current rating if it is wired in full-winding and set it to the unipolar current rating if wired in half-winding.
Eight-wire motors are about 3% more efficient when parallel-connected than an equivalent half-winding connected six-wire motor, but are considerably more complicated to connect. There is no advantage when comparing a series connection to a full-winding connection. As in a six-wire motor, the choice between series versus parallel connection is application dependent. Remember to set the drive current to exactly half of the motor’s rated parallel (as wired in Figure 11) current rating when using the series connection shown in Figure 12.
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