Example of Calculations for Backplane Current Requirements 

In this example, the system includes:

• One seven-slot modular rack

• One 1747-L543 CPU module

• One 1746-IB8 DC input module with eight inputs @ +24V

• One 1746-OV8 DC output module with eight outputs @ +24V

• An SLC Servo Module system that contains:

• SLC Servo Modules

• Termination panels

• Allen-Bradley 845H encoders

• Fast inputs

• Fast outputs

Using Fast Inputs and Outputs

The fast I/O (FIN1through FIN3, and FOUT1) are 24V DC compatible 

and are used with a user-side +24V power supply. Review potential

24V DC I/O devices for compatibility with the electrical specifications 

as shown in the table below.