24. The Configuration Files
INI : The ini file overrides defaults that are compiled into the
LinuxCNC code.
HAL: The HAL files start up process modules and provide
linkages between LinuxCNC signals and specific hardware
pins.
VAR: The var file is a way for the interpreter to save some
values from one run to the next. These values are saved from
one run to another but not always saved immediately.
TBL:The tbl file saves tool information.
NML: The nml file configures the communication channels
used by the LinuxCNC. It is normally setup to run all of the
communication within a single computer but can be modified
to communicate between several computers.
25. The Configuration Files
The INI File Components
Comments
Sections
Variables
Custom Sections and Variables
26. The Configuration Files
Hardware Abstraction Layer (HAL)
Component
Parameter
Pin
Physical_Pin
Signal
Type
Function
Thread
27. Hardware Abstraction Layer
(HAL)
Component
A HAL component is a piece of software with well-defined inputs, outputs,
and behavior, that can be installed and interconnected as needed.
Parameter
Many hardware components have adjustments that are not connected
to any other components but still need to be accessed. There are two
types of parameters: input & Output .
Pin
Hardware components have terminals which are used to interconnect
them. The HAL equivalent is a pin or HAL pin. HAL pins are software entities
that exist only inside the computer.
Physical_Pin
Many I/O devices have real physical pins or terminals that connect to
external hardware. To avoid confusion, these are referred to as physical
pins. These are the things that stick out into the real world.
28. Hardware Abstraction Layer
(HAL)
Signal
In a physical machine, the terminals of real hardware components are
interconnected by wires.
Type
Bit - a single TRUE/FALSE or ON/OFF value
float - a 64 bit floating point value, with approximately 53 bits of resolution
and over 1000 bits of dynamic range.
u32 - a 32 bit unsigned integer, legal values are 0 to 4,294,967,295
s32 - a 32 bit signed integer, legal values are -2,147,483,647 to
+2,147,483,647
Both pins and signals have types, and signals can only be connected to
pins of the same type
29. Hardware Abstraction Layer
(HAL)
Function
Each function is a block of code that performs a specific action. The
system integrator can use threads to schedule a series of functions to be
executed in a particular order and at specific time intervals.
Thread
A thread is a list of functions that runs at specific intervals as part of a
realtime task. When a thread is first created, it has a specific time interval
(period), but no functions. Functions can be added to the thread, and will
be executed in order every time the thread runs.
30. Hardware Abstraction Layer
(HAL)
HAL Commands
loadrt
The command loadrt loads a real time HAL component. Real time
component functions need to be added to a thread to be updated
at the rate of the thread
addf
The command addf adds a real time component function to a
thread. You have to add a function from a HAL real time component
to a thread to get the function to update at the rate of the thread.
31. Hardware Abstraction Layer
(HAL)
HAL Commands
loadusr
The command loadusr loads a user space HAL component. User
space programs are their own separate processes, which optionally
talk to other HAL components via pins and parameters. You cannot
load real time components into user space.
net
The command net creates a connection between a signal and and
one or more pins. If the signal does not exist net creates the new
signal.
32. Hardware Abstraction Layer
(HAL)
HAL Commands
setp
The command setp sets the value of a pin or parameter. The valid
values will depend on the type of the pin or parameter.
unlinkp
The command unlinkp unlinks a pin from the connected signal. If no
signal was connected to the pin prior running the command, nothing
happens.
