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Precautions for simultaneous input of the START
signal to multiple UJ20 controllers
One START signal can be simultaneously input to multiple UJ20 controllers.
Add diodes to the terminals to prevent input signal currents from leaking.
There are no problems when only one controller is used. However, as shown in Figure 1,
when one of multiple controllers is powered on and the others are powered off, a small
current from the START terminal of the ON-controller passes the START terminals of the
OFF-controllers, their internal boards, and then the GND terminals. The leak current will
cause the controller to misjudge that a START signal has been input.
Figure 1
START
POWER
POWER
= ON
COMMON
(GND)
As shown in Figure 2, add general rectifier diodes to the terminals to rectify the
current flow.
The signal current is approx. 15 mA. Also take the same measures for the input
terminals other than the START signal terminals.
START
START
POWER
= OFF
= OFF
COMMON
COMMON
(GND)
(GND)
Figure 1
START
P O W E R
P OW E R
= OFF
= ON
COMMON
(GND)
24
Equipment
design
START
START
P O W E R
= OFF
COMMON
COMMON
(GND)
(GND)
Matsushita Electric Works, Ltd.
Global Marketing Division
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