Custom Mcode message queue

stuartofmt

The macro (below) implemets a "private" message queue. It's a multi-message buffer, not a FIFO queue.

Hopefully others find this post useful.

Background
In one of my programs / plugin (DuetLapse3), I originally started using M117 and later M291 / M292. The semantics were not right for my use-case and could cause undesirable side effects / interactions. This macro resolves those issues.

Operation

The operation is as follows (assumes the macro is /sys/M3291) :

An array global.DL3msg stores the messages. The first element [0] is a sequence counter.
A string array global.DL3Del lists the indexes of messages that are to be deleted.
There are two reserved messages M3291 B"Del" and M291 B"Clear"

Adding a message

The macro is called with a single parameter that is the message. e.g. M3291 B"A Message"
The message is added to the first empty(nul) element in global.DL3msg
The message sequence counter global.DL3.msg[0] is incremented

Reading Messages (typical use-case)

The reciever reads global.DL3msg
If the sequence number global.DL3msg[0] has been incremented
- Copies any non-null elements noting the index
- Place indexes into an array
- use the array to update the delete list e.g. set global.DL3del = {2,5,6,}
- calls M3291 B"Del" to delete the now, read messages.

Deleting Messages

The macro is called with M3291 B"Del
- For each element in global.DL3Del the corresponding index in global.DL3msg is set to null i.e. deletes the message
- global.DL3Del is set to null i.e. no messages to be deleted

Clearing Messages

The macro is called with `M3291 B"Clear"
- All messages in global.DL3msg are cleared.
- The sequence number global.DL3msg[0] is retained.

M3291 macro

; A message passing queue for use by DuetLapse3
; This is not used as a FIFO queue - its a multi-message buffer.

; The macro should be placed in /sys folder and given a name like
; M3921 (the default)
;
; If the name is changed e.g. to avoid a custom M code conflict (should always be M<something>)
; the -M3291 option of DuetLapse3 needs to be set to the new name
;
; Useage:
; M3921 B"<DuetLapse3 command message>"
; e.g. M3921 B"Duetlapse3.start"
; Can only take one message per call
;
; Special Useage:
; M3921 B"Clear"    (Case Sensitive)
; Clears the queue and leaves the sequence number at last value.  May be useful between print jobs
;
; M3921 B"Del"    (Case Sensitive)
; Deletes items from the queue based on indexes held in global.DL3del
;
; DL3msg queue uses the following structures
; global.DL3msg[0]  int - sequence number of last message added.
; global.DL3msg[x]  string -  the message to be processed
;
; global.DL3del  string array -  indexes in DL3msg to be deleted
; e.g.  set global.DL3del = {1,3,7,}
;
; At the processing end, if global.DL3msg[0] is > last time checked: all messages are extracted in one go
; global.DL3del is set with a list of extracted messge indexes
; and then M321 P"Del" called.  i.e. the recently read entries are cleared
;
; #################  MACRO STARTS HERE #################################
; Version number of this macro
var version = "Version 1.0"
;
; Make sure queue is initialized
; number of messages that can be held. 15 should be good for most cases
var len_DL3msg = 15

if !exists(global.DL3msg) || global.DL3msg=null
	;initialize the message queue
	global DL3msg = vector(var.len_DL3msg,null)
	;beginning sequence number
	set global.DL3msg[0] = 0

	if !exists(global.DL3del) || global.DL3del=null
		; initialize the delete array
		global DL3del = null

	echo "DL3msg queue: initialized"
	echo var.version

; check if B parameter sent
if exists(param.B)
	var Bparam = param.B

	if var.Bparam = "Clear"
		; Clear the queue
		; sets all message slots to null but leaves the sequence number as-is
		; clear the delete array
		var sequence = global.DL3msg[0]
		set global.DL3msg = vector(var.len_DL3msg,null)
		set global.DL3msg[0] = var.sequence 
		set global.DL3del = null
		echo "DL3msg queue:  Cleared"

	elif var.Bparam = "Del"
		; Delete (make null) selected messages from DL3msg queue
		; This allows bulk deletes
		; Items to be deleted are held in an array in global.DL3del
		if global.DL3del != null            ; there are items to delete
			while true
				if iterations >= #global.DL3del
					break
				set global.DL3msg[global.DL3del[iterations]] = null
			echo "DL3msg queue:  Items deleted - "^global.DL3del
			set global.DL3del = null
		else
			echo "DL3msg queue:  Nothing to delete"

	else
		; Add new message to the queue
		; Iterate through and place message in any emply (null) slot
		; If all the slots are full -- no more can be added				
		var success = false
		while true
			if iterations >= var.len_DL3msg
				break
			if global.DL3msg[iterations] == null
				set global.DL3msg[0] = global.DL3msg[0] + 1 ; increment message count
				set global.DL3msg[iterations] = var.Bparam
				set var.success = true
				echo "DL3msg queue: Added - "^var.Bparam^" as item "^iterations 
				break

		; Check if message added OK		
		if !var.success
			var errormsg = "DL3msg queue:  Full"
			echo var.errormsg
			M291 P{var.errormsg} S0

else
	echo var.version
	echo "DL3msg queue: No B param passed"

T3P3Tony

@stuartofmt cool!, what are you using this for?

stuartofmt

@T3P3Tony

DuetLapse3 has the ability to accept commands at runtime and modify its behavior. For example, change certain options, start / stop the timelapse recording, invoke a local programs / scripts.

It periodically checks to see if there is some command that needs action. The M3291 macro provides a fairly failsafe and non-blocking way to communicate. It also does not have any side effects if DuetLapse3 is not running (blocking M291 messages were a bit of a pain).

For example (you'll be sorry you asked):
I usually have DuetLapse3 in standby mode (doing nothing). I also usually have it set to capture images on layer change and also every 'n' seconds.

In my slicer's start gcode, after heating homing etc I issue a M3291 message that tells DuetLapse3 to start the timelapse. This avoids capturing images during the preample.

In my slicer's end gcode, I issue a M3291 message that tells DuetLapse3 to stop recording every 'n' seconds and to stop the timelapse. This avoids capturing images of non-printing moves (e.g. dropping the bed).

Another use might be to have different types of timelapse settings in macros that call M3291 messages. This way DuetLapse3 can be modified by calling the relevent macro (at the start of a print job). This avoids the need to modify the configuration file and restart DuetLapse3.

T3P3Tony

@stuartofmt thanks for the detail!

sankafola

@stuartofmt said in Custom Mcode message queue:

@T3P3Tony

DuetLapse3 has the ability to accept commands at runtime and modify its behavior. For example, change certain options, start / stop the timelapse recording, invoke a local programs / scripts.

It periodically checks to see if there is some command that needs action. The M3291 macro provides a fairly failsafe and non-blocking way to communicate. It also does not have any side effects if DuetLapse3 is not running (blocking M291 messages were a bit of a pain).

For example (you'll be sorry you asked):
I usually have DuetLapse3 in standby mode (doing nothing). I also usually have it set to capture images on layer change and also every 'n' seconds.

In my slicer's start gcode, after heating homing etc I issue a M3291 message that tells DuetLapse3 to start the timelapse. This avoids capturing images during the preample.

In my slicer's end gcode, I issue a M3291 message that tells DuetLapse3 to stop recording every 'n' seconds and to stop the timelapse. This avoids capturing images of non-printing moves (e.g. dropping the bed).

Another use might be to have different types of timelapse settings in macros that call M3291 messages. This way DuetLapse3 can be modified by calling the relevent macro (at the start of a print job). This avoids the need to modify the configuration file and restart DuetLapse3.

hi @stuartofmt , am getting this error

stuartofmt

@sankafola
You have cross posted this question. Lets keep the discussion in the other post since its not clear at this point if you even have a clean install.