Project:RELaserSoftware/MOL file format: Difference between revisions

= Description =

== About ==

== Status ==

== The File Format ==

== The Header ==

The header chunk contains the parameters of the destination machine, version numbers, and general information including file size. All data is at fixed positions.

== The Config Chunk ==

This block has all the information about the position and size of the artwork. It uses, like the following chunks, a number of binary commands, most of them deciphered below.

== The Test Chunk ==

This is called when the "Test" button is pressed on the panel. It moves the laser head around the bounding box of the artwork and is a great help for positioning the material. In this file, it is simply a bunch of line drawing commands.

== The Draw Chunk ==

This is called when the "Play" button is pressed and contains a setup part followed by a list of machine control commands that cut and draw the artwork.

== Binary Commands ==

Every command starts with three bytes describing the command itself, plus one byte containing the number of parameters following. The parameters are always 4-byte words in LSB integer or floating point format, or four individual bytes. The FP format differs slightly from the IEEE standard, but can be converted by shifting a few bits around.  

The size byte can be 0x80 in which case, the actual number of arguments is give in the 4-byte integer that follows.

A special command (0x46 0x09 0x00 0x80 0xnnnnnnnn) encapsulates n motion commands. The motion commands follow the same scheme as all other binary commands. This is likely used for multiple prints of the same drawing in a matrix layout.

= Sample File =

The header describes the parameters of the machine for which the data was created. We find information about the file size and the stepper resolution. There should not be any information how to map channels to motors, etc., as that is likely done in a separate configuration file.

This word changes when the size of the file changes, i.e. when lines are added. This line corresponds to the number of "move relative" commands in the entire file counting "unknown 07" and "unknown 09" as well. Is that coincidence? What would this value be good for? perhaps estimating the cutting time?

The configuration chunk still has a bunch of unknown commands, few of them seem to change for a single machine configuration.

* arg2 is the start speed for all head movements as described in the settings

This is the block that is called when the user presses "Test" on the panel. It moves the laser head on the bounding box around the artwork.

Begin of the subroutine. I don't know if the ID has a specific meaning, or if the file position of this block is sufficient to make it the test block. Just don't change it.

This command encloses all following draw commands. It may be used for multiple rendering of the drawing commands at different location to keep file size small. The commands inside the block follow the same scheme as those outside.  

acceleration, constant speed(optional), deceleration. All three put together move the head from a to b along a straight line. If the angle of two consecutive lines is below some threshold, the end speed of the previous line and the initial speed of the current

Move the head on a straight line to the new position. The position is given in steps relative to the current position. The meaning of 772 (0x0304) is unknown but could very well be the index of the stepper that is requested to move (3=Y, 4=X - remember that this is LSB, so in the binary file, we see 0x04 0x03 0x00 0x00 - maybe we can move Z as well, or even up to four axes at the same time? (2=Z))

Even though we still are in acceleration mode, setting the initial speed equal to the maximum speed will make this a constant speed motion.

Set the next speed parameters so that they are used for deceleration from the maximum speed (b) to the ending speed (a), using the deceleration parameter (c)

Motion Command Block. These blocks seem to divide the file into 2kByte chunks at command boundaries. Command blocks never contain more than 510 (512?) words (<=2kBytes). This subroutine can ahve many command blocks. Motion Commands are switching periphery (laser, lower), setting acceleration and deceleration, and moving the head.

Switch on the blower. The numerical values here probably correspond to the output ports on the controller board. If we find the pattern, we can control additional devices, like switching the Y axis to control a rotary device, or starting the roller of a laser sintering setup.

Switch the laser off already. Even though the next line requires no repositioning, LaserCut has switched off the laser, just to turn it right back on. This does no harm, but makes the file bigger then needed. It also explains why we should always "connect lines" in LaserCut. If lines are connected, we would simply add movement commands here until we reach the end of the cut.

Leaves the head just where it's at. In case of a repetition, the controller will likely know where to move next and continue with the next cutout.

The rest of the file is filled with 0x00 to the next 512 byte boundary, probably to avoid readingerrors when buffering from the USB stick to internal RAM.

= Hexdump =