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TA4 Lua Controller

The TA4 Lua Controller is a small computer, programmable in Lua to control your machinery. In contrast to the ICTA Controller this controller allows to implement larger and more complex programs.

But to write Lua scripts, some knowledge with the programming language Lua is required.

Minetest uses Lua 5.1. The reference document for Lua 5.1 is here. The book Programming in Lua (first edition) is also a perfect source for learning Lua.

This TA4 Lua Controller manual is also available as PDF:

https://github.com/joe7575/techage/blob/master/manuals/ta4_lua_controller_EN.pdf

TA4 Lua Controller Blocks
Lua Functions and Environment
Lua Controller Functions
Example Scripts

TA4 Lua Controller Blocks

TA4 Lua Controller

The controller block has a menu form with the following tabs:

the init tab for the initialization code block
the func tab for the Lua functions
the loop tab for the main code block
the outp tab for debugging outputs via $print()
the notes tab for your code snippets or other notes (like a clipboard)
the help tab with information to the available functions

The controller needs power to work. A battery pack has to be placed nearby.

Battery

The battery pack has to be placed near the controller (1 block distance). The needed battery power is directly dependent on the CPU time the controller consumes. Because of that, it is important to optimize the execution time of the code (which helps the admin to keep server lags down :))

The controller will be restarted (init() is called) every time the Minetest server starts again. To store data non-volatile (to pass a server restart), the "TA4 Lua Server" block has to be used.

TA4 Lua Server

The Server block is used to store data from Lua Controllers nonvolatile. It can also be used for communication purposes between several Lua Controllers. Only configured players have access to the server. Therefore, the server has a menu to enter player names.

For special Server functions, see "Server and Terminal Functions"

TA4 Lua Controller Terminal

The Terminal is used to send command strings to the controller. In turn, the controller can send text strings to the terminal. The Terminal has a help system for internal commands. Its supports the following commands:

clear = clear the screen
help = output this message
pub = switch terminal to public use (everybody can enter commands)
priv = switch terminal to private use (only the owner can enter commands)
send <num> on/off = send on/off event to e. g. lamps (for testing purposes)
msg <num> <text> = send a text message to another Controller (for testing purposes)

For special Terminal functions for the TA4 Lua Controller, see "Server and Terminal Functions"

TA4 Sensor Chest

tbd.

Lua Functions and Environment

Lua Functions and Limitations

The controller uses a subset of the language Lua, called SaferLua. It allows the safe and secure execution of Lua scripts, but has the following limitations:

limited code length
limited execution time
limited memory use
limited possibilities to call functions

SaferLua follows the standard Lua syntax with the following restrictions:

no while or repeat loops (to prevent endless loops)
no table constructor {..}, see "Arrays, Stores, and Sets" for comfortable alternatives
limited runtime environment

SaferLua directly supports the following standard functions:

math.floor
math.abs
math.max
math.min
math.random
tonumber
tostring
unpack
type
string.byte
string.char
string.find
string.format
string.gmatch
string.gsub
string.len
string.lower
string.match
string.rep
string.sub
string.upper
string.split (result is an Array)
string.split2 (result are multiple returns like the Lua function unpack)
string.trim

For own function definitions, the menu tab 'func' can be used. Here you write your functions like:

function foo(a, b)
    return a + b
end

Each SaferLua program has access to the following system variables:

ticks - a counter which increments by one each call of loop()
elapsed - the amount of seconds since the last call of loop()
event - a boolean flag (true/false) to signal the execution of loop() based on an occurred event

Arrays, Stores, and Sets

It is not possible to easily control the memory usage of a Lua table at runtime. Therefore, Lua tables can't be used for SaferLua programs. Because of this, there are the following alternatives, which are secure shells over the Lua table type:

Arrays

Arrays are lists of elements, which can be addressed by means of an index. An index must be an integer number. The first element in an array has the index value 1. Arrays have the following methods:

add(value) - add a new element at the end of the array
set(idx, value) - overwrite an existing array element on index idx
get(idx) - return the value of the array element on index idx
remove(idx) - remove the array element on index idx
insert(idx, val) - insert a new element at index idx (the array becomes one element longer)
size() - return the number of array elements
memsize() - return the needed array memory space
next() - for loop iterator function, returning idx,val
sort(reverse) - sort the array elements in place. If reverse is true, sort in descending order.

Example:

a = Array(1,2,3,4)     --> {1,2,3,4}
a.add(6)               --> {1,2,3,4,6}
a.set(2, 8)            --> {1,8,3,4,6}
a.get(2)               --> function returns 8
a.insert(5,7)          --> {1,8,3,4,7,6}
a.remove(3)            --> {1,8,4,7,6}
a.insert(1, "hello")   --> {"hello",1,8,4,7,6}
a.size()               --> function returns 6
a.memsize()            --> function returns 10
for idx,val in a.next() do
    ...
end

Stores

Unlike arrays, which are indexed by a range of numbers, stores are indexed by keys, which can be a string or a number. The main operations on a store are storing a value with some key and extracting the value given the key. The store has the following methods:

set(key, val) - store/overwrite the value val behind the keyword key
get(key) - read the value behind key
del(key) - delete a value
size() - return the number of store elements
memsize() - return the needed store memory space
next() - for loop iterator function, returning key,val
keys(order) - return an array with the keys. If order is "up" or "down", return the keys as sorted array, in order of the store values.

Example:

s = Store("a", 4, "b", 5)  --> {a = 4, b = 5}
s.set("val", 12)           --> {a = 4, b = 5, val = 12}
s.get("val")               --> returns 12
s.set(0, "hello")          --> {a = 4, b = 5, val = 12, [0] = "hello"}
s.del("val")               --> {a = 4, b = 5, [0] = "hello"}
s.size()                   --> function returns 3
s.memsize()                --> function returns 9
for key,val in s.next() do
    ...
end

Keys sort example:

s = Store()            --> {}
s.set("Joe", 800)      --> {Joe=800}
s.set("Susi", 1000)    --> {Joe=800, Susi=1000}
s.set("Tom", 60)       --> {Joe=800, Susi=1000, Tom=60}
s.keys()               --> {Joe, Susi, Tom}
s.keys("down")         --> {Susi, Joe, Tom}
s.keys("up")           --> {Tom, Joe, Susi}

Sets

A set is an unordered collection with no duplicate elements. The basic use of a set is to test if an element is in the set, e.g. if a player name is stored in the set. The set has the following methods:

add(val) - add a value to the set
del(val) - delete a value from the set
has(val) - test if value is stored in the set
size() - return the number of set elements
memsize() - return the needed set memory space
next() - for loop iterator function, returning idx,val

Example:

s = Set("Tom", "Lucy")     --> {Tom = true, Lucy = true}
s.add("Susi")              --> {Tom = true, Lucy = true, Susi = true}
s.del("Tom")               --> {Lucy = true, Susi = true}
s.has("Susi")              --> function returns `true`
s.has("Mike")              --> function returns `false`
s.size()                   --> function returns 2
s.memsize()                --> function returns 8
for idx,val in s.next() do
    ...
end

All three types of data structures allow nested elements, e.g. you can store a set in a store or an array and so on. But note that the overall size over all data structures can't exceed the predefined limit. This value is configurable for the server admin. The default value is 1000. The configured limit can be determined via memsize():

memsize()  --> function returns 1000  (example)

Initialization, Cyclic Task, and Events

The TA4 Lua Controller distinguishes between the initialization phase (just after the controller was started) and the continuous operational phase, in which the normal code is executed.

Initialization

During the initialization phase the function init() is executed once. The init() function is typically used to initialize variables, clean the display, or reset other blocks:

-- initialize variables
counter = 1
table = Store()
player_name = "unknown"

# reset blocks
$clear_screen("123")      -- "123" is the number of the display
$send_cmnd("2345", "off")  -- turn off the blocks with the number "2345"

Cyclic Task

During the continuous operational phase the loop() function is cyclically called. Code witch should be executed cyclically has to be placed here. The cycle frequency is per default once per second but can be changed via:

$loopcycle(0)   -- no loop cyle any more
$loopcycle(1)   -- call the loop function every second
$loopcycle(10)  -- call the loop function every 10 seconds

The provided number must be an integer value. The cycle frequency can be changed in the init() function, but also in the loop() function.

Events

To be able to react directly on received commands, the TA4 Lua Controller supports events. Events are usually turned off, but can be activated with the function events():

$events(true)    -- enable events
$events(false)   -- disable events

If an event occurs (a command was received from another block), the loop() is executed (in addition to the normal loop cycle). In this case the system variable 'event' is set:

if event then
    -- event has occurred
    if $get_input("3456") == "on" then  -- check input from block "3456"
        -- do some action...
    end
end

The first occurred event will directly be processed, further events may be delayed. The TA4 Lua Controller allows a maximum of one event every 100 ms.

Lua Controller Functions

In addition to Lua standard function the Lua Controller provides the following functions:

Controller local Functions

$print(text) - Output a text string on the 'outp' tab of the controller menu. E.g.: $print("Hello "..name)
$loopcycle(seconds) - This function allows to change the call frequency of the controller loop() function, witch is per default one second. For more info, see "Cyclic Task"
$events(bool) - Enable/disable event handling. For more info, see "Events"
$get_ms_time() - Returns the time with millisecond precision
get_gametime() - Returns the time, in seconds, since the world was created
$time_as_str() - Read the time of day (ingame) as text string in 24h format, like "18:45"
$time_as_num() - Read the time of day (ingame) as integer number in 24h format, like 1845
$get_input(num) - Read an input value provided by an external block with the given number num. The block has to be configured with the number of the controller to be able to send status messages (on/off commands) to the controller. num is the number of the remote block, like "1234".

Input Example

A Player Detector with number "456" is configured to send on/off commands to the TA4 Lua Controller with number "345".
The TA4 Lua Controller will receive these commands as input value.
The program on the SaferLua Controller can always read the last input value from the Player Detector with number "456" by means of:

sts = $get_input("456")

Techage Command Functions

With the $send_cmnd(num, ident, add_data) function, you can send commands to and retrieve data from another block with the given number num. The possible commands can be classified in two groups: Commands for reading data and commands for triggering an action. Please note, that this is not a technical distinction, only a logical.

Reading data

ident specifies the data to be read.
add_data is for additional data and normally not needed.
The result is block dependent (see table below)

ident	returned data	comment
"state"	one of: "running", "stopped", "blocked", "standby", "fault", or "unloaded"	Techage machine state, used by many machines
"state"	one of: "red", "amber", "green", "off"	Signal Tower state
"state"	one of: "empty", "loaded", "full"	State of a chest or Sensor Chest
"fuel"	number	fuel value of a fuel consuming block
"depth"	number	Read the current depth value of a quarry block (1..80)
"load"	number	Read the load value in percent (0..100) of a tank, silo, accu, or battery block, or from the Signs Bot Box. Silo and tank return two values: The percentage value and the absolute value in units. Example: percent, absolute = $send_cmnd("223", "load")
"delivered"	number	Read the current delivered power value of a generator block. A power consuming block (accu) provides a negative value
"flowrate"	Total flow rate in liquid units	Only for TA4 Pumps
"action"	player-name, action-string	Only for Sensor Chests
"stacks"	Array with up to 4 Stores with the inventory content (see example)	Only for Sensor Chests
"count"	number	Read the item counter of the TA4 Item Detector block
"count"	number of items	Read the total amount of TA4 chest items. An optional number as `add_data` is used to address only one inventory slot (1..8, from left to right).
"itemstring"	item string of the given slot	Specific command for the TA4 8x2000 Chest to read the item type (technical name) of one chest slot, specified via `add_data` (1..8). Example: s = $send_cmnd("223", "itemstring", 1)
"output"	recipe output string, e.g.: "default:glass"	Only for the Industrial Furnace. If no recipe is active, the command returns "unknown"
"input"	<index>	Read a recipe from the TA4 Recipe Block. `<index>` is the number of the recipe. The block return a list of recipe items.
"name"	<player name>	Player name of the TA3/TA4 Player Detector or TA4 Button
"time"	number	Time in system ticks (norm. 100 ms) when the TA4 Button is clicked

Trigger an action

num is the number of the remote block, like "1234"
cmnd is the command
data is additional data (see table below)

cmnd	data	comment
"on", "off"	nil	turn a node on/off (machine, lamp,...)
"red, "amber", "green", "off"	nil	set Signal Tower color
"red, "amber", "green", "off"	lamp number (1..4)	Set the signal lamp color. Valid for "TA4 2x Signal Lamp" and "TA4 4x Signal Lamp"
"port"	string `<color>=on/off`	Enable/disable a Distributor filter slot.. Example: `"yellow=on"` colors: red, green, blue, yellow
"config"	"<slot> <item list>"	Configure a Distributor filter slot, like: "red default:dirt dye:blue"
"text"	text string	Text to be used for the Sensor Chest menu
"reset"	nil	Reset the item counter of the TA4 Item Detector block
"pull"	item string	Start the TA4 pusher to pull/push items. Example: `default:dirt 8`
"config"	item string	Configure the TA4 pusher. Example: `wool:blue`
"exchange"	inventory slot number	TA3 Door Controller II (techage:ta3_doorcontroller2) Exchange a block idx is the inventory slot number (1..n) of/for the block to be exchanged
"set"	inventory slot number	TA3 Door Controller II (techage:ta3_doorcontroller2) Set/add a block idx is the inventory slot number (1..n) with the block to be set
"dig"	inventory slot number	TA3 Door Controller II (techage:ta3_doorcontroller2) Dig/remove a block idx is the empty inventory slot number (1..n) for the block
"a2b"	nil	TA4 Move Controller command to move the block(s) from position A to B
"b2a"	nil	TA4 Move Controller command to move the block(s) from position B to A
"move"	nil	TA4 Move Controller command to move the block(s) to the opposite position
"move2"	x,y,z	TA4 Move Controller command to move the block(s) by the given x/y/z-distance. Valid ranges for x, y, and z are -100 to 100.
"reset"	nil	Reset TA4 Move Controller (move block(s) to start position)
"left"	nil	TA4 Turn Controller command to turn the block(s) to the left
"right"	nil	TA4 Turn Controller command to turn the block(s) to the right
"uturn"	nil	TA4 Turn Controller command to turn the block(s) 180 degrees
"recipe"	`<item_name>,<item_name>,...`	Set the TA4 Autocrafter recipe. Example for the torch recipe: `default:coal_lump,,,default:stick` Hint: Empty fields may only be left out at the end of the item list!
"recipe"	`<number>.<index>`	Set the TA4 Autocrafter recipe with a recipe from a TA4 Recipe Block. `<number>` is the TA4 Recipe Block number `<index>` is the number of the recipe in the TA4 Recipe Block
"goto"	`<slot>`	Start command for the TA4 Sequencer. `<slot>` is the time slot like `[1]` where the execution starts.
"stop"	nil	Stop command for the TA4 Sequencer.
"gain"	volume	Set volume of the sound block (`volume` is a value between 0 and 1.0)
"sound"	index	Select sound sample of the sound block

Server and Terminal Functions

The Server is used to store data permanently/non-volatile. It can also be used to share data between several Controllers.

$server_write(num, key, value) - Store a value on the server under the key key. key must be a string. value can be either a number, string, boolean, nil or data structure. This function does not allow nested data structures. num is the number of the Server. Example: $server_write("0123", "state", state)
$server_read(num, key) - Read a value from the server. key must be a string. num is the number of the Server, like "1234".

The Terminal can send text strings as events to the Controller. In contrast the Controller can send text strings to the terminal.

$get_term() - Read a text command received from the Terminal
$put_term(num, text) - Send a text string to the Terminal. num is the number of the Terminal.

Communication between Lua Controllers

Messages are used to transport data between Controllers. Messages can contain arbitrary data. Incoming messages are stored in order (up to 10) and can be read one after the other.

$get_msg([raw]) - Read a received message. The function returns the sender number and the message. (see example "Emails"). If the raw parameter is not set or false, the message is guaranteed to be a string.
$send_msg(num, msg) - Send a message to another Controller. num is the destination number. (see example "Emails")

Further Functions

$chat(text) - Send yourself a chat message. text is a text string.
$door(pos, text) - Open/Close a door at position "pos".
Example: $door("123,7,-1200", "close").
Hint: Use the Techage Info Tool to determine the door position.
$item_description("default:apple") Get the description (item name) for a specified itemstring, e. g. determined via the TA4 8x2000 Chest command itemstring: str = $send_cmnd("223", "itemstring", 1) descr = $item_description(str)
$display(num, row, text) Send a text string to the display with number num. row is the display row, a value from 1 to 5, or 0 to add the text string at the bottom (scroll screen mode). text is the string to be displayed. If the first char of the string is a blank, the text will be horizontally centered.
$clear_screen(num) Clear the screen of the display with number num.
$position(num) Returns the position as string "'(x,y,z)" of the device with the given num.

Example Scripts

Simple Counter

Very simple example with output on the Controller menu.

init() code:

a = 1

loop() code:

a = a + 1
$print("a = "..a)

Hello World

"Hello world" example with output on the Display.

init() code:

a = Array("Hello", "world", "of", "Minetest")

$clear_screen("0669")

for i,text in a.next() do
    $display("0669", i, text)
end

For Loop with range(from, to)

Second "Hello world" example with output on the Display, implemented by means of a for/range loop.

init() code:

a = Array("Hello", "world", "of", "Minetest")

$clear_screen("0669")

for i in range(1, 4) do
	text = a.get(i)
	$display("0669", i, text)
end

Monitoring Chest & Furnace

More realistic example to read Pusher states and output them on a display:

init() code:

DISPLAY = "1234"  -- adapt this to your display number
min = 0

loop() code:

-- call code every 60 sec
if ticks % 60 == 0 then
    -- output time in minutes
    min = min + 1
    $display(DISPLAY, 1, min.." min")

    -- Cactus chest overrun
    sts = $send_cmnd("1034", "state") -- read pusher status
    if sts == "blocked" then $display(DISPLAY, 2, "Cactus full") end

    -- Tree chest overrun
    sts = $send_cmnd("1065", "state")  -- read pusher status
    if sts == "blocked" then $display(DISPLAY, 3, "Tree full") end

    -- Furnace fuel empty
    sts = $send_cmnd("1544", "state")  -- read pusher status
    if sts == "standby" then $display(DISPLAY, 4, "Furnace fuel") end
end

Simple Calculator

A simple calculator (adds entered numbers) by means of a Lua Controller and a Terminal.

init() code:

$events(true)
$loopcycle(0)

TERM = "360" -- terminal number, to be adapted!
sum = 0
$put_term(TERM, "sum = "..sum)

loop() code:

s = $get_term() -- read text from terminal
if s then
    val = tonumber(s) or 0  -- convert to number
    sum = sum + val
    text = string.format("+%d = %d", val, sum) -- format output string
    $put_term(TERM, text)  -- output to terminal
end

Welcome Display

In addition to the controller, you also need a player detector and a display. When the Player Detector detects a player the player name is shown on the display:

init() code:

$events(true)
$loopcycle(0)

SENSOR = "365"   -- player detector number, to be adapted!
DISPLAY = "367"  -- display number, to be adapted!

$clear_screen(DISPLAY)

loop() code:

if event then
    name = $send_cmnd(SENSOR, "name")
    if name == "" then -- no player arround
        $clear_screen(DISPLAY)
    else
        $display(DISPLAY, 2, " Welcome")
        $display(DISPLAY, 3, " "..name)
    end
end

Sensor Chest

The following example shows the functions/commands to be used with the Sensor Chest:

init() code:

$events(true)
$loopcycle(0)

SENSOR = "372"   -- sensor chest number, to be adapted!

$send_cmnd(SENSOR, "text", "press both buttons and\nput something into the chest")

loop() code:

if event and $get_input(SENSOR) == "on" then
    -- read inventory state
    state = $send_cmnd(SENSOR, "state")
    $print("state: "..state)
    -- read player name and action
    name, action = $send_cmnd(SENSOR, "action")
    $print("action"..": "..name.." "..action)
    -- read inventory content
    stacks = $send_cmnd(SENSOR, "stacks")
    for i,stack in stacks.next() do
        $print("stack: "..stack.get("name").."  "..stack.get("count"))
    end
    $print("")
end

Emails

For an email system you need a TA4 Lua Server and a TA4 Lua Controller with Terminal per player. The TA4 Lua Server serves as database for player name/block number resolution.

Each Player needs its own Terminal and Controller. The Terminal has to be connected with the Controller
Each Controller runs the same Lua Script, only the numbers and the owner names are different
To send a message, enter the receiver name and the text message like Tom: hello into the Terminal
The Lua script will determine the destination number and send the message to the destination Controller
All players who should be able to take part in the email system have to be entered into the Server form

init() code:

$loopcycle(0)
$events(true)

-- Start: update to your conditions
TERM = "360"
CONTROLLER = "359"
NAME = "Tom"
SERVER = "363"
-- End: update to your conditions

$print($server_write(SERVER, NAME, CONTROLLER))
$print($server_write(SERVER, CONTROLLER, NAME))

loop() code:

-- read from Terminal and send the message
s = $get_term()
if s then
    name,text = string.split2(s, ":", false, 1)
    num = $server_read(SERVER, name)
    if num then
        $send_msg(num, text)
        $put_term(TERM, "message sent")
    end
end
    
-- read message and output to terminal
num,text = $get_msg()
if num then
    name = $server_read(SERVER, num)
    if name then
        $put_term(TERM, name..": "..text)
    end
end

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TA4 Lua Controller

Table of Contents

TA4 Lua Controller Blocks

TA4 Lua Controller

Battery

TA4 Lua Server

TA4 Lua Controller Terminal

TA4 Sensor Chest

Lua Functions and Environment

Lua Functions and Limitations

Arrays, Stores, and Sets

Arrays

Stores

Sets

Initialization, Cyclic Task, and Events

Initialization

Cyclic Task

Events

Lua Controller Functions

Controller local Functions

Input Example

Techage Command Functions

Server and Terminal Functions

Communication between Lua Controllers

Further Functions

Example Scripts

Simple Counter

Hello World

For Loop with range(from, to)

Monitoring Chest & Furnace

Simple Calculator

Welcome Display

Sensor Chest

Emails

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