The 1756-A17 is not a PLC programmer but an Allen-Bradley ControlLogix chassis. It is a rack-mountable chassis that provides a physical housing for various modules, including PLC processors, communication modules, analog I/O modules, and digital I/O modules.

To program the Allen-Bradley ControlLogix PLC, you would typically use programming software such as RSLogix 5000 or Studio 5000. These software tools allow you to create, edit, and monitor the ladder logic, function block diagrams, and other programming elements of the ControlLogix PLC.

Here's a general overview of the process to program a ControlLogix PLC:

Install and Set up the Programming Software: Install the appropriate version of RSLogix 5000 or Studio 5000 on your computer. Follow the software installation instructions provided by Rockwell Automation. Once installed, configure the software to communicate with your PLC hardware.

Create a New Project: Open the programming software and create a new project. Specify the target ControlLogix PLC model and select the communication method, such as Ethernet or serial connection.

Configure Hardware: Configure the hardware configuration within the software by defining the modules installed in the ControlLogix chassis. This includes specifying the types and addresses of the modules, such as digital I/O, analog I/O, and communication modules.

Develop the Program Logic: Use the programming software's graphical editor to develop the program logic. This typically involves creating ladder logic diagrams, function block diagrams, or other programming methods supported by the software. You can define inputs, outputs, timers, counters, and program flow using the available programming instructions.

Download the Program: Once the program logic is developed, download it to the ControlLogix PLC. This step transfers the program from the software to the PLC hardware. Ensure that the proper connection is established between the programming software and the PLC.

Test and Debug: After downloading the program, you can run it on the ControlLogix PLC. Monitor the program execution, test inputs and outputs, and make any necessary adjustments or modifications to the logic to ensure desired behavior.