added docmentation for dashio_data_exporter

Author: James Boulton

Documents/dashio_data_exporter.md

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+# How to Access Data from the DashIO Server
+
+This guide explains how to retrieve data from the DashIO server for time graphs, maps, and logs using the utility `dashio_data_exporter` included in the dashio library package.
+
+## Prerequisites
+
+- Python 3
+- DashIO library package
+
+## Installation
+
+```bash
+pip3 install dashio
+```
+
+The data retrieval script is included as a utility in the dashio package.
+
+## Basic Usage
+
+```bash
+python -m dashio.utilities.get_data -u USERNAME -p PASSWORD -d DEVICE_ID -c CONTROL_ID [options]
+```
+
+## Command Line Arguments
+
+| Argument | Description |
+|----------|-------------|
+| `-u`, `--username` | Your DashIO username |
+| `-p`, `--password` | Your DashIO password |
+| `-d`, `--device_id` | The ID of the device to access |
+| `-c`, `--control_id` | The ID of the control to access |
+| `-t`, `--type` | Control type: `TGRPH` (time graph), `MAP`, or `LOG` (default: `TGRPH`) |
+| `-n`, `--number_of_days` | Number of days of data to retrieve (default: 1) |
+| `-f`, `--format` | Output format: `raw` or `csv` (default: `raw`) |
+| `-s`, `--screen` | Display output to the screen |
+| `-o`, `--outfile` | Write output to file(s) |
+
+## Examples
+
+### Retrieving Time Graph Data
+
+```bash
+python -m dashio.utilities.get_data -u myusername -p mypassword -d mydevice -c mygraph -t TGRPH -n 3 -s
+```
+
+This retrieves 3 days of time graph data for the specified device and control, displaying the output on screen.
+
+### Saving Map Data to a File
+
+```bash
+python -m dashio.utilities.get_data -u myusername -p mypassword -d mydevice -c mymap -t MAP -f csv -o
+```
+
+This retrieves map data in CSV format and saves it to a file.
+
+### Getting Log Data
+
+```bash
+python -m dashio.utilities.get_data -u myusername -p mypassword -d mydevice -c mylog -t LOG -s -o
+```
+
+This retrieves log data, displaying it on screen and saving it to a file.
+
+## Output File Naming
+
+When using the `-o` option, files are named using the pattern:
+```
+[device_id]_[control_type]_[control_id]_[line_id].[format]
+```
+
+## Understanding Output Formats
+
+### Raw Format
+
+The raw format preserves the original structure from the server with tab-separated values:
+```
+[device_id]  [control_type]  [control_id]  [data...]
+```
+
+### CSV Format
+
+The CSV format converts time graph data to a more readable format:
+```
+# [device_id], TGRPH, [control_id], [line_id], [line_name], [line_type], [line_color], [line_axis]
+Timestamp, Value
+[timestamp], [value]
+[timestamp], [value]
+...
+```