1. SECTION 1 ADAMS/Solver subroutines overview
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2. WHAT IS IN THIS SECTION Why use subroutines?
Incorporation into a model
Running Adams with a custom library

3. WHY USE SUBROUTINES
Subroutines are used to override the standard functionality in Adams/Solver.
Examples of such situations include:
Implementing complex logic that might be difficult using Adams/Solver function expressions
Incorporating existing code for specialty mechanical elements
Example – a mature control system created for vehicle handling control
Including proprietary mechanical elements
Example – equations for a proprietary spring-damper system can be ‘hidden’ within a subroutine and distributed safely to others
When you need to interact with other software or complex data files

4. INCORPORATING INTO A MODEL
The Adams model must be set up properly so that Adams/Solver knows to use user-written code for the particular element(s).
The Adams/Solver manual shows the following syntax for many of the statements in an Adams/Solver dataset (.adm) file: where:
e refers to an expression using Adams/Solver built-in function expressions, for example: STEP(time,1,0,10,10)
USER()indicates that the Solver must call a provided user-written subroutine for this element. For example, if you had a subroutine that expected to be passed a spring constant followed by a damper constant then the expression might be: USER(120.0,10.1) where the spring and damper constants are and 10.1 respectively. The input parameters can be anything that is defined by the user-written subroutine.

5. INCORPORATING INTO A MODEL (CONT.)
Here is an example of a single component force element statement in an Adams/Solver dataset that uses standard function expressions:
SFORCE/1, TRANSLATIONAL, I=10, J=11, ACTIONONLY, FUNCTION= STEP(TIME,0,0,12.5,200)
This same SFORCE element could be instructed to calculate its value from a user-written subroutine if it was rewritten as:
SFORCE/1, TRANSLATIONAL, I=10, J=11, ACTIONONLY, FUNCTION= USER(120,10.1)
Adams/View has a toggle for most function expression fields that lets one use either standard function expressions or user-written code. The Define Using field for most elements in Adams/View has the options Subroutine and Function.

6. RUNNING ADAMS WITH A CUSTOM LIBRARY
Specifying a user-written subroutine in the model file lets Adams/Solver know to look for a user library which calculates values
User-written code libraries are typically stored in files of type:
.dll (dynamically linked/loaded library) on Windows
.so (shared object) on Linux
This user library must be specified before running a simulation
There are three ways to specify an Adams/Solver user library before running a simulation. They are detailed in the following table.
Product
Specification
Notes
Adams/Solver
adams2013 ru-user library_name.dll
Start with ‘ru-user’ flag and specify a library to use
Adams/View
Settings → Solver → Solver Executable
Set ‘Solver Library’ field in this dialog box
adams2013 aview ru-user i -n library_name.dll
Start View with ‘ru-user’, specify a Solver library but not a View library

7. RUNNING ADAMS WITH A CUSTOM LIBRARY
For example: adams2013 ru-user mysolver.dll run_commands.acf
Would run Adams/Solver from the command line on Windows, using Adams v2013
The custom library mysolver.dll would be loaded at runtime
The run_commands.acf file would specify the Solver commands needed to exercise the model

8. EXERCISE
Perform Workshop 1 “Custom Tire Subroutine” in your exercise workbook