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Using Intelligent Input Terminals Section 4-5
4-5-9 Three-wire Interface Operation
The 3-wire interface is an industry standard motor control interface. This func-
tion uses two inputs for momentary contact start/stop control, and a third for
selecting forward or reverse direction. To implement the 3-wire interface,
assign
20 [STA] (Start), 21 [STP] (Stop), and 22 [F/R] (Forward/Reverse) to
three of the intelligent input terminals. Use a momentary contact for Start and
Stop. Use a selector switch, such as SPST for the Forward/Reverse input. Be
sure to set the operation command selection
A002=01 for input terminal control
of motor.
If you have a motor control interface that needs logic-level control (rather than
momentary pulse control), use the [FW] and [RV] inputs instead.
The diagram below shows the use of 3-wire control. STA (Start Motor) is an
edge-sensitive input; an OFF-to-ON transition gives the Start command. The
control of direction is level-sensitive, and the direction may be changed at any
time. STP (Stop Motor) is also a level-sensitive input.
Option
Code
Terminal
Symbol
Function
Name
State Description
20 STA Start Motor ON Start motor rotation on momentary
contact (uses acceleration profile)
OFF No change to motor operation
21 STP Stop Motor ON No change to motor operation
OFF Stop motor rotation on momentary
contact (use deceleration profile)
22 F/R Forward/
Reverse
ON Select reverse direction of rotation
OFF Select forward direction of rotation
Valid for inputs: C001~C007
Required settings: A002 = 01
Notes:
• The STP logic is inverted. Normally the switch will be closed, so you open the
switch to stop. In this way, a broken wire causes the motor to stop automatically
(safe design).
• When you configure the inverter for 3-wire interface control, the dedicated [FW] ter-
minal is automatically disabled. The [RV] intelligent terminal assignment is also dis-
abled.
[STP] terminal
1
0
t
[F/R] terminal
1
0
Motor revolution
speed
[STA] terminal
1
0
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