Update README

README.md

@@ -1,2 +1,18 @@
 # node-red-contrib-openplc
-This package contains two nodes, one that represents an OpenPLC instance and one function node that transforms incoming messages to attach a PLC address to them so the OpenPLC node knows where to send the data.
+This package makes it possible to configure and interact with an OpenPLC instance from within Node-RED.
+
+Two nodes are included in the package. The `OpenPLC` node represents the OpenPLC instance and is used to communicate with the PLC. Messages sent to this node will set registers of the PLC using the Modbus protcol. The outputs of this node can represent both digital and analog outputs. The `OpenPLC-Input` node is used to attach a PLC address to incoming data. The output of this node can immediately be sent to the `OpenPLC` node.
+
+## Installation
+Install using npm in your Node-RED directory:
+```
+npm install node-red-contrib-openplc
+```
+
+## Example
+The included example flow has a button which will keep a lamp on for a specified amount of time. This duration parameter can also be configured. The use of both digital and analog outputs is demonstrated.
+
+![Example](examples/button-lamp.png)
+
+## Acknowledgements
+This package uses the Modbus configuration node from [node-red-contrib-modbus](https://github.com/biancode/node-red-contrib-modbus) by Klaus Landsdorf.