4.22Logic Studio

Logic Studio is the visual logic builder of the gateway. You draw a scheme of blocks, connect them with links, and the gateway keeps evaluating it, reading KNX values and writing KNX results. This page lists the dialogs, every block type and how the gateway runs a scheme.

#What it does

A logic function is one scheme. A scheme has input blocks that bring in values (a KNX group address, a constant), processing blocks (logic gates, maths, timers, counters, analog filters, a script) and output blocks that write the result to a KNX group address. Typical uses are a light that follows a motion sensor with a timer, a fan that follows two conditions, or a counter of how long a pump has run.

Logic Studio publishes no System Objects. Its results leave as KNX telegrams, so a page object shows a result by being bound to the output's group address.

#Before you enable it

• The service is Disabled by default. Turn Enabled on and deploy the project (see Deploying to a gateway). Each function also has its own Enabled switch.
• Logic Studio reads and writes the KNX bus through the gateway's KNX connection, so the KNX engine must be working.
• Save in the dialog (Save Changes) and deploy again after every change.

#Settings

#The Logic Studio dialog

The left column lists the functions as 1-Logic Function 1 with an Enabled or Disabled tag. Add creates a function, Clone Function copies the selected one (with Copy added to its name) and Remove deletes it. Selecting a function shows its properties:

Import and Export in the header save and load all functions as logic-studio-functions.json. Importing replaces every function. A file that is not a Logic Studio file shows "Invalid Logic Studio file." Unlike the other dialogs, Save Changes here saves the session ("Logic Studio saved."), and Cancel or the close button asks you to confirm before it discards unsaved changes.

#The scheme editor

Select a function and press Click to edit... to open the editor. It has three parts: the function list and Block Palette on the left, the canvas in the middle and the Properties inspector on the right. Back to collection returns to the function list.

• Add a block: drag an entry from the palette onto the canvas, double-click it, or select it and press Add Block. Search blocks... filters the palette by name. The palette groups are Inputs, Outputs, Analog, Counters, Logic, Math, Timers, Scripting, Logic Module Sheet, Conditions and Comment.
• Connect blocks: drag from the out point of a block to one of the input points of another. A block shows one input point per input (set by Inputs, 1 to 64), from top to bottom, and the block grows taller to hold them. Where the order of the inputs is fixed, the points are named (On/Off Delay: Input and Reset; Comparator: Input 1 and Input 2), otherwise they are numbered. Dropping a link on a point that already has one replaces it. A block with a gate also has a gate point. Click a link to select it, and use its x button to remove it. The inspector's Connect to list does the same without dragging, and a selected link has an Input port list to move it to another point.
• Toolbar: the function name, the function's Enabled switch, Live gateway test, the Grid switch and grid size (5 to 100, default 20), zoom out and in (10 to 200 percent), 100% and Fit. Ctrl and the mouse wheel also zoom. The canvas starts at 1040 by 560 units and grows as you place blocks further right or down, so a scheme with many blocks (for example 15 inputs feeding one Or) always has room.
• Live gateway test: with Value labels shown, each block displays its current value. The editor reads it every second from the gateway, so the project must be deployed and the gateway reachable from the Configurator.

#Block properties

Select a block to see its inspector. These fields exist for every block type.

A link has a name, a source and target block, and an Enabled switch. A disabled link is ignored.

#Block reference

A value counts as true when it is 1, true, on, yes or any number other than 0. A logic result is written as 1 or 0.

#Inputs

#Outputs

#Logic

#Math

Math blocks use only the numeric inputs and produce a number. A block with no numeric input gives no output.

All math blocks are run.

#Timers

Times use Milliseconds, Seconds, Minutes or Hours (default Seconds). Timer state is kept in memory and is lost on a restart. The gateway checks timers once a second, so times are accurate to about a second.

#Analog

#Counters

Counters keep their totals in gateway storage when Reboot survive is on (the default), so they survive a restart. They use the block's Output setting. Besides the choices in the table, Interval and Threshold show Store time interval (ms) (default 60000) and Change percentage (default 5).

#Scripting and comments

#Logic Module Sheet and Conditions

The Logic Module Sheet blocks start something, and the Conditions blocks test a value. Blocks that report an event answer with a pulse: 1 in the evaluation in which the event happened, 0 in the next. Link a pulse to a Command, Network Output or Set Value Store block (set to On trigger) to run it once per event.

Operator for Compare, Range Check and Threshold Filter: Equals, Not equals, Greater than, Less than, Between (the compare value is min,max; 10..20 and 10;20 also work) and Contains (the text of input 1 contains the compare value). Numbers are compared as numbers and anything else as text. Changed, Rising Edge and Falling Edge ignore the operator.

#How it works on the gateway

• The gateway evaluates every enabled function once a second. It also evaluates the function at once when a KNX write or response telegram arrives for a group address used by one of its KNX Input blocks.
• Each evaluation runs every block repeatedly, so the order of the blocks on the canvas does not matter.
• A KNX output writes only when its value changed since its last write, with one exception: the first evaluation after the gateway starts writes the output's current value. A scheme that ends in a timer therefore writes 0 at start.
• Inputs that have no value yet make dependent blocks wait. An And with one input that has no value gives 0.
• The gateway sees its own writes as incoming telegrams. Do not feed a block from the same group address it writes to.
• Counter totals with Reboot survive are saved in gateway storage. Everything else, including latches and timers, starts empty after a restart.

#Example 1: motion sensor to light with a timer

The light follows a motion sensor and stays on for 5 minutes after the last movement.

1. Add a function named Corridor light and open the scheme.
2. Add a KNX Input: KNX Group 1/2/10, Input type DPT 1.001, Value at startup 0 until first telegram.
3. Add a Stairwell Lighting Switch: Time for ON 300 with Time base for ON Seconds, Warning before OFF 10 seconds, Retriggerable on, Manual OFF off, Output connector Output.
4. Add a KNX Output: Group address 1/1/21, Output type DPT 1.001.
5. Link KNX Input to the Stairwell block, and the Stairwell block to the KNX Output.
6. Save and deploy. A movement telegram (1) on 1/2/10 writes 1 to 1/1/21. Each new movement restarts the 5 minutes. When the time ends the gateway writes 0.

#Example 2: only when it is dark

Add the lux sensor so the light only comes on at night:

1. Add a KNX Input 1/2/11, Input type DPT 9.004, Value at startup Wait for a new telegram, and a Range Verifier with Threshold Min. 0 and Threshold Max. 50. Link the input to the Range Verifier.
2. Add an And. Link the motion KNX Input and the Range Verifier to it.
3. Link the And to the Stairwell block instead of the motion input.

Now motion only starts the timer while the lux value is between 0 and 50. In daylight the And gives 0.

#Example 3: mains failure that survives one phase still being on

In many places a power cut drops one or two phases while the third stays on, sometimes at only about 100 V. A check "all three phases are zero" then never fires. Use the lowest phase instead.

1. Add three KNX Input blocks, one for each phase voltage of the meter, Input type the data type your meter uses for voltage.
2. Add a Min block with Inputs 3. Link the phases to its input points 1, 2 and 3.
3. Add a Constant Value, Value type Number, Value 240 (the normal voltage).
4. Add a Comparator / 2 Points Regulator. Link the Min to its point Input 1 and the constant to Input 2. Set Threshold for ON 70 and Threshold for OFF 40.
5. Add a KNX Output for the "mains failed" flag and link the Comparator to it.

The Comparator turns on when the lowest phase is more than 70 V away from 240 V (below about 170 V), and turns off again when it is less than 40 V away (above about 200 V). Between the two it holds, so a voltage that wobbles around the limit does not switch the flag back and forth. A normal supply at 245 V is only 5 V from 240 V and stays off.

#Example 4: a battery percentage flag

Send a flag to the bus when a UPS battery falls below 90 percent:

1. Add a KNX Input for the battery percentage and a Constant Value 100.
2. Add a Comparator with Threshold for ON 10 and Threshold for OFF 5. Link the battery to Input 1 and the constant to Input 2.
3. Link the Comparator to a KNX Output.

The flag turns on when the battery falls below 90 percent and off again when it rises above 95 percent.

#Tips and common problems

• Nothing happens at all: check that Logic Studio is Enabled in the Server tab, that the function is Enabled, that you saved and deployed, and that the Live test shows values on the blocks.
• A timer block never starts: Continuous Pulse Generator, Random Generator and Scheduled Pulse start with their Gate on. Link a block that carries 1 to the gate point, or turn the gate off.
• A block shows --: it has no value yet. For a KNX Input, set Value at startup or wait for the first telegram.
• The light switches off when the gateway restarts: the first evaluation writes the output's current value. Design the scheme so that this value is the one you want.

#See also

• Rule gateway
• Automation
• Formula engine
• Network I/O gateway
• KNX engine
• KNX basics for installers