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1–4
Introduction
System Power
External Power
Publication 1771 UM006B-EN-P - June 2002
System power is supplied through the I/O chassis backplane from the
5V dc chassis power supply. The module requires a current of 1.4A.
The sum of the current requirements of all modules in the chassis
must not exceed the power supply or backplane rating.
The module requires an external power supply connected to the field
wiring arm. For the 1771-IJ, the supply must be able to deliver
140mA at 5V dc +0.25V with less than 50mV ripple, peak-to-peak.
The 1771-IK requires 110mA at 12V dc or 200mA at 24V dc, with
less than 50mV ripple, peak-to-peak. These requirements are for the
module only. The current requirements of all output devices, if they
are to be driven directly from the module, must be added to the
requirements of the module.
It is also possible to drive output devices from a separate load supply,
using the output on the module only as a switch. When the output is
on and conducting, a maximum of 0.5V dc is dropped across it. The
load supply voltage should not exceed 30V dc. Refer to Figure 1.3
for the necessary modifications to the wiring diagram.
Figure 1.3
Modification of Output Circuit for Application of Separate Load Power Supply
Right
Swing Arm
External
Module
11
Module
2 or 4
Output
Transistor
12
If multiple sources are used, maintain isolation between supplies.
The power for the input device can be provided by the module's
external power supply, but, unlike the power for the output device,
this is not available through the module. If a high degree of isolation
is needed, use a separate input power supply. If a limit switch is
used, the limit switch input is configured to accept an "on" voltage
of 12 to 48V dc, requiring a maximum of 10mA at 48V dc.
Module
+
-
External
Supply
Output Return
Common
Load
+
-
Power
Supply
Load
15944
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