Three-Wire Interface Operation - Omron MX2 User Manual

Using Intelligent Input Terminals
4-5-9

Three-wire Interface Operation

186
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,
20
assign [STA] (Start),
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
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.
Option Terminal
Code Symbol
20
STA Start Motor
21
STP Stop Motor
22
F/R Forward/
Reverse
C001~C007
Valid for inputs:
A002 = 01
Required settings:
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.
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.
1
[STA] terminal
0
1
[STP] terminal
0
1
[F/R] terminal
0
Motor revolution
speed
21 22
[STP] (Stop), and
A002
Function State
Name
ON Start motor rotation on momentary
contact (uses acceleration profile)
OFF No change to motor operation
ON No change to motor operation
OFF Stop motor rotation on momentary
contact (use deceleration profile)
ON Select reverse direction of rotation
OFF Select forward direction of rotation
Section 4-5
[F/R] (Forward/Reverse) to
01
= for input terminal control
Description
t