24 KiB
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
Table of Contents
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 screenhelp
= output this messagepub
= 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
orrepeat
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
- 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, returningidx,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 keywordkey
- 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, returningkey,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, returningidx,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"$get_ms_time()
- Returns time with millisecond precision$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
$read_data(num, ident, add_data)
- Read any kind of data from another block with the given number num. 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 from fuel consuming block |
"load" | number | Read the load value in percent (0..100) from a tank/storage block, an accu block, of from the Signs Bot Box. |
"delivered" | number | Read the current delivered power value from a generator block. A power consuming block (accu) provides a negative value |
"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 on inventory slot (1..8, from left to right). |
$send_cmnd(num, cmnd, data)
- Send a command to another block. 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", "green", "blue", "yellow" | "on", "off" | Enable/disable a Distributor filter slot. |
"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 |
$display(num, row, text)
Send a text string to the display with number num. row is the display row, a value from 1 to 5, or 0 to add the text string at the bottom (scroll screen mode). text is the string to be displayed. If the first char of the string is a blank, the text will be horizontally centered.$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.
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.
Further Functions
Messages are used to transport data between Controllers. Messages are text strings or any other data. Incoming messages are stored in order (up to 10) and can be read one after the other.
-
$get_msg()
- Read a received message. The function returns the sender number and the message. (see example "Emails") -
$send_msg(num, msg)
- Send a message to another Controller. num is the destination number. (see example "Emails") -
$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.
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 = $read_data("1034", "state") -- read pusher status
if sts == "blocked" then $display(DISPLAY, 2, "Cactus full") end
-- Tree chest overrun
sts = $read_data("1065", "state") -- read pusher status
if sts == "blocked" then $display(DISPLAY, 3, "Tree full") end
-- Furnace fuel empty
sts = $read_data("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 = $read_data(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 = $read_data(SENSOR, "state")
$print("state: "..state)
-- read player name and action
name, action = $read_data(SENSOR, "action")
$print("action"..": "..name.." "..action)
-- read inventory content
stacks = $read_data(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 = unpack(string.split(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