# Energy Meter In Block

This block reads back the input data from the LEGO Energy Meter. The following input data are read back from the Energy Meter: input voltage (V), input current (A), input wattage (W) and input joule (J). All inputs are read back with the same resolution as they are displayed on the Energy Meter. The data source are selected within configuration panel and will then be available within the output drawer called "Sensor reading" for further use within the program. It is also possible to send out a logic signal (true/false) based on whether the current data value falls above or below a trigger point.

A trigger point is the specific value in a range of numbers where a change in condition occurs. For example, you might program your robot to give a signal when the joule level get below 30. The trigger point would be 30.

Specify the trigger point by using the slider or by typing a number into the input box. To specify the range (above or below the trigger point) that will generate the “true” signal, use the radio buttons or the pull-down menu. The “true” portion of the range will be in color; the “false” portion will be gray.

The default setting for the Energy Meter block is levels below 5 to generate a “true” signal. The radio button to the right of the range is selected and the slider is set at 5. To switch the “true” portions of the range (setting values below 5 as “true”), you would select the left radio button.

You must drag at least one output data wire from this block’s data hub to another block for any information to be sent.

## Display Settings

1. The number shows which of your NXT’s ports are connected to the Energy Meter. You can change this number in the configuration panel if you need to.
2. The block's data hub will open automatically when the block is placed in the work area. At least one data wire must be dragged from the block's output plug to another block's data hub.(See the Data Hub section below for more information.)

## Configuring the Energy Meter In Block

1. Choose the port where the Energy Meter is plugged in. By default, the block will be set to port 3 for a Energy Meter. You can change this selection if you need to.
2. Use the slider to set the trigger value or type a value directly into the input box. Select the radio button to the right of the slider if you want the block to be triggered by values higher than the trigger value; select the left radio button to trigger the block with values lower than the trigger value. You can also use the pull-down menu to set the “true” portion of the slider.
3. Selects the data source type to be used. By default the data source type is set to input voltage (V) but it is possible to change it to either: input current (A), input wattage (W) or joule (J)
4. The feedback box displays the current reading (depending on data source type selected).

## Configuring the Energy Meter In block’s Data Hub

You can control the Energy Meter In block dynamically by connecting data wires (from other blocks’ data hubs) to the Energy Meter In block’s data hub.

Open a block’s data hub by clicking the tab at the lower left edge of the block after it has been placed on the work area.

Data wires carrying input information to a block are connected to the plugs on the left side of its data hub. Data wires carrying output information are connected to the plugs on the right side.

[A] Input plug
[B] Output plug
[C] Number data wire (yellow)
[D] Logic data wire (green)
[E] Text data wire (orange)
[F] Broken data wire (gray)

### Passing data from the input plug to the output plug

If an input plug has a corresponding output plug (see A above), the input data will pass through from the input plug to the output plug without being changed. In this case, you can only use the output plug if the input plug is connected to an input data wire; connecting an output data wire to such an output plug without a connected input data wire will cause the output data wire to be “broken” (and colored gray).

### Data wires carry specific types of data

Each data wire carries a specific type of data between blocks. For example, if a data wire is dragged from a logic plug on a block’s data hub, it can only be connected to a logic plug on another block’s data hub. The chart below shows what kind of data each plug can accept or send out.

### Data wire colors

Data wires are identified with specific colors: wires carrying number data are colored yellow, wires carrying logic data are colored green, and wires carrying text data are colored orange.

### “Broken” data wires

If you try to connect a data wire to a plug of the wrong data type, the data wire will be broken (and colored gray). You will not be able to download your program if a data wire is broken.

If you click a broken wire you can read why it is broken in the small help window in the lower right corner of the work area.

### Data must be within the possible range of the plug

If an input data wire transmits a value outside the possible range of the plug it is connected to, the block will either ignore the value or change it to a value within its range. For plugs that allow just a few input values (example: just 0, 1, or 2), the plug will ignore the input if a value arrives outside its range.

For plugs that accept larger input ranges (example: 0 – 100), the plug will force any input outside its range to fit. For example, if a Move block’s Power plug receives an input value of 150, the block will change the input value to 100 (i.e., a number within the Power plug’s range).

### This chart shows the different characteristics of the plugs on the Energy Meter In block’s data hub:

| Plug | Data Type | Possible Range | What the Values Mean | This Plug is Ignored When...
| Port | Number | 1 - 4 | 1 = Port 1, 2 = Port 2, 3 = Port 3, 4 = Port 4 |
| Trigger Point | Number | Voltage in: 0.0-10.0 (V) Current in: 0.0-0.3 (A) Wattage in: 0.0-3.0 (W) Joule: 0-100 (J) | Value to compare against |
| Greater / Less | Logic | True/False | Logic used in comparison: True = Greater, False = Less |
| Source type | Number | Mode 0:Voltage in Mode 1:Current in Mode 2:Wattage in Mode 3:Joule | Data number for selecting data source type |
| Yes / No | Logic | True/False | Result of comparison |
| Sensor Reading | Number | Voltage in: 0.0-10.0 (V) Current in: 0.0-0.3 (A) Wattage in: 0.0-3.0 (W) Joule: 0-100 (J) | Scaled value read from sensor. |