1. PLC 5 and ControlLogix Subroutine Parameters

2. Input Parameters Simple Example
Three variable frequency drives heat sink temperatures input to PLC
Temperatures input in degrees Celsius
Convert to degrees Fahrenheit and display on operator interface

3. Option #1 Ladder Conversion
Each time temperature input could add a rung to do calculations.
This would make ladder file longer.
More rungs
Slower scan

4. Option #2 Subroutine Conversion
Put conversion instructions in a subroutine
Access subroutine each time conversion necessary
Less rungs in ladder
JSR input parameters used to move temperature data to subroutine

5. JSR Instructions with Parameters

6. Heat Sink Temperature from Three Different Sources
Drive node 21 temperature to F8:0
Drive node 22 temperature to F8:1
Drive node 23 temperature to F8:2

7. JSR Sends Information to SBR
JSR sends temperature information to
SBR instruction input parameter address F8:10.
Node 21, F8:0 temperature
Node 22, F8:1 temperature
Node 23, F8:2 temperature

8. Subroutine Shares Data
- F8:10 is where temperature is stored.
- F8:10 data used in calculation

9. CPT Destination Stores Result

10. Result, F8:11 to RET Output Parameter

11. Data Returned to JSR Data from RET instruction return parameter to JSR
return parameter F8:12

12. Data Flow
Ladder 2 A D E
Ladder 3 C B

13. No Return Parameter Faults Processor