Allen-Bradley 6189V-OB36 Instructions D'installation page 8

8 Digital Output Accessory
ATTENTION
The transient energy is dissipated in the load, and the pulse duration is longer for
loads of high impedance. The graph below illustrates the relation between pulse
duration and load current. Transient pulse duration will not exceed the time shown
in the graph. For most applications, the pulse energy is not sufficient to energize
the load.
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
The recommended wiring method is to connect the external supply directly to the
+VDC and DC COM terminals. The voltage rate of change is then limited by the
power up characteristics of the supply, and the stray transient pulses may be
avoided.
Publication 6180W-IN003B-MU-P
A brief transient current pulse may flow through the digital
outputs if the external supply voltage is suddenly connected to
the +VDC or the DC COM terminal (for example through a relay
or other hard-contact switch). It is the fast rate of change of
voltage at the terminals that causes the pulse. This condition is
inherent in transistor outputs and is common to solid state
devices. The transient pulses may occur whether the 1200W
computer is running or not, and without regard to the status of
the keys of the 1200W keypad.
Transient Pulse Duration as a
Function of Load Current
100
On-State Load Current (mA)
200 300