Rockwell Automation 1764-xxxx MICROLOGIX 1500 PROGRAMMABLE CONTROLLERS - Manual (Page 147)

1 Publication 1764-UM001B-EN-P - April 2002
Appendix
F
System Loading and Heat Dissipation
System Loading Limitations When you connect MicroLogix accessories and expansion I/O, an
electrical load is placed on the base unit power supply. This section
shows how to calculate the load and validate that the system will not
exceed the capacity of the base unit power supply or expansion
power supply.
The following example is provided to illustrate system loading
validation. The system validation procedure accounts for the amount
of 5V dc and 24V dc current consumed by controller, expansion I/O,
and user supplied equipment.
Current consumed by the Base Units, Memory Modules, Real Time
Clock Modules, and the End Cap Terminators (for systems utilizing
Compact I/O expansion) has already been factored into the
calculations. A system is valid if the current and power requirements
are satisfied.
System Expansion
Calculations A download is also available for system validation. On the Internet, go
to http://www.ab.com/micrologix and navigate to MicroLogix 1500.
The procedure in this publication consists of:
•
Selecting System Devices
•
Verifying the System Loading
TIP
An End Cap Terminator (catalog number 1769-ECR
or -ECL) is needed for any system using Compact
expansion I/O.
IMPORTANT
In a MicroLogix 1500 system, a maximum of one 1769
expansion cable can be used, allowing for two banks
of I/O modules. One bank is connected directly to
the controller and the other is connected via the
expansion cable. The bank connected to the
controller uses the controller’s embedded power
supply. The bank connected via the cable requires its
own power supply.