otk c++ assemble component in given assembly using Coordinatesystems

Here the Tcl code, check the comments, about 11 commands and the component is assembled.

I hope that helps to understand the process. You can use less than 11 lines, if you later understand what you doing here😉 You only need to map this to toolkit calls, probably > 11

# are comments 

#———————————————-

# Vars for the models to be used

set ASSY assy.asm

set PART mode.prt

# Create two selection objects

# including named model items

# one for the assembly reference

# one for the component reference

# Note: The model item is initialized

ps_sel AssySelObj -modelitem AssyMiObj

ps_sel CompSelObj -modelitem CompMiObj

# A csys for sure has a name

# Note: The Feature ID of the CSYS is not the ID, which is used later

# The Geometric ID will be used

# set data, fill csys geometric id, type and owner.

#

# one for the assembly

# one for the component

# This two calls will setup the model items with valid values

# if the given name and type is valid

# the csys names are ACS0 and CS0

# now fill the modelitem by name and type

AssyMiObj byname $ASSY csys ACS0

CompMiObj byname $PART csys CS0

#

# create the constraint Object

#

ps_asmconstraint constraintObj

#

# setup the type by 'csys'

#

constraintObj         config -constrainttype   CSYS

#

# set the info, same as manually done in Creo after selecting the references

# Could be done in one statement as well

#

constraintObj         config -asmselection   AssySelObj -asmdatumside none

constraintObj         config -compselection  CompSelObj -compdatumside NONE

#

# Create a default matrix for initial position

#

ps_matrix matrixObj

#

# Assemble the component first without any constraints

# You only have to take care that

# 'PlacedMiObj' does not exists as a command with another type.

# You can create it upfront as well, same for the Matrix Object

#

ps_assy assemble -model $ASSY -- $PART matrixObj PlacedMiObj

# Final call to set the constraints

# We don't need to specify a component path in this sample

# The path argument are not given to the function

# because we assemble to the toplevel csys of the assembly and we assemble a single component

# 'PlacedMiObj' is the result from assembling without constraints

# this uniquely identifies the component to configure

# 'list' is used to keep in mind that you may need to specify more the one constraint

# If you assemble by datum planes you need to supply normally 3 constraints

#

# If this fail, you may want to delete the placed component with ps_feat delete ?ID?

# The feature id you get with: 'PlacedMiObj cget -id'

#

# Configure the placed component to make if fully parametric

#

ps_assy setconstraints PlacedMiObj  [list asmconObj]

# Component is now fully constraint and assembled by csys

#———————————————-

there is a sample code in protk_appls\pt_examples\pt_asm\TestAsm.c in protoolkit installation folder. Probably this is what you are looking for...