Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual User Manual
Page 52
Publication 1747-UM011G-EN-P - June 2008
52
Selecting Your Hardware Components
Transient Pulse
To reduce the possibility of inadvertent operation of devices
connected to transistor outputs, adhere to the following guidelines:
•
Either ensure that any programmable device connected to the
transistor output is programmed to ignore all output signals until
after the transient pulse has ended,
•
Add an external resistor in parallel to the load to increase the
on-state load current. The duration of the transient pulse is
reduced when the on-state load current is increased.
The duration of the transient pulse is proportional to the load
impedance. This is illustrated in the following graph.
Transient Pulse/Load Impedance Graph
Duration of Transient (T)
Time
(On-State Load
Current)
Cur
rent
Tr
an
sien
t (I)
0
1000
1
2
3
4
5
6
7
8
9
10
1
100
200
300
400
500
600
700
800
900
On-State Load Current (mA)
Du
ra
tion
o
f T
ran
sie
nt
(ms
)