Three-wire interface operation – Hitachi L300P User Manual
Page 158
Using Intelligent Input Terminals
Oper
ations
a
nd Moni
tor
ing
4–28
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.
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.
Opt.
Code
Symbol
Function Name
Input
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
(uses deceleration profile)
22
F/R
Forward/Reverse
ON
Select reverse direction of rotation
OFF
Select forward direction of rotation
Valid for
inputs:
C001, C002, C003, C004,
C005
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] terminal
is automatically disabled. The [RV] intelligent
terminal assignment is also disabled.
5
3
1
4
2
FW
TH
PLC
P24
CM1
See I/O specs on page
STA
F/R
STP
Example (requires input configuration—
see page
):
[STA] terminal
[F/R] terminal
[STP] terminal
Motor revolution speed
Forward
Reverse
t