Lab 8 - Analog Control



To explore analog inputs and outputs on PLCs and mathematical calculations.


Pre-Lab: (due at the start of lab period)

1. Write simple programs to read an input voltage and output the same analog voltages from the PLC.

2. Develop the ladder logic to read an analog voltage, perform a calculation, and output the result as an analog voltage. The equation is,



Process Description:

Analog inputs and outputs are done with multipurpose cards in the PLC rack. To control these cards there is some overhead required to set voltage ranges, scales, values, etc. This can be done by setting values in the PLC memory, or by using built in setup functions.




SoftLogix controller and FlexIO rack with an IE4XOE2 analog IO module

Computer with RS-Logix programming software


Power Supplies



1. Configure the PLC as normal. Ensure that when setting up the the card the inputs and outputs are set to the -10V to 10V range. The card will also require a 24V supply - refer to the installation manual for additional details.

2. Test the analog output values using a multimeter. Change the output value (Ch0OutputData) and measure the output voltage. Repeat this for multiple values and record the results in a table. Draw a graph. Please note that when ‘validating’ you should take multiple readings at the ends and middle of the data range with special attention to the regions with the greatest amount of change. Values should be compared with ideal in a graph or table.

3. Supply an input voltage between (but not beyond +/-10V) and record the input voltage and integer value in a table. Then graph the values.

4. Test the program written for prelab step 1.

5. Test the program written for prelab step 2 and test with a multimeter and voltage supply. Use a number of values to confirm.




1. Pre-lab and updated laboratory materials.

2. The documentation should contain details of ALL of the settings not evident in the program.

3. Detailed test results for the input/output calculation.



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