Three-Wire Interface Operation - Hitachi L300P Series Instruction Manual

4–28
Using Intelligent Input Terminals
Three-wire
Interface
Operation
The 3-wire interface is an industry standard motor control interface. This function 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 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.
Opt.
Symbol Function Name
Code
20 STA Start Motor
21 STP Stop Motor
22 F/R Forward/Reverse
C001, C002, C003, C004,
Valid for
C005
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] terminal
is automatically disabled. The [RV] intelligent
terminal assignment is also disabled.
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.
[STA] terminal
[STP] terminal
[F/R] terminal
Motor revolution speed
Input
Description
State
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
(uses deceleration profile)
ON Select reverse direction of rotation
OFF Select forward direction of rotation
Example: (Requires input configuration—
see page 3–43. Jumper position shown is
for –xFU/-xFR models; for –xFE models,
see page 4–11.)
TH FW
5
P24 PLC CM1
See I/O specs on page 4–8.
Forward
Reverse
STP
F/R STA
4 3 2 1
t