Send Modbus Data to GIS Software using MQTT/JSON

Goals

The ski and snowboard resort industry in the US alone is a multi-billion dollar industry. As is the case with virtually every industry, technology is playing an ever-increasing roll in how these resorts operate. Snow making systems allow ski resorts to extend their seasons and continue to operate when relying on mother nature alone would not. Automated snow making systems monitor weather conditions at different locations throughout the resorts. Snow depth is typically measured using an ultrasonic or radar sensor. Other sensors are used to measure temperature and humidity at various locations. Ski resorts also track trail maintenance with snowcats and trail groomers. Using GIS software, such as ArcGis by ESRI, they can map out all of this information for analysis and make educated decisions.

Solution Description

Open Automation Software’s built in MQTT broker allows for the transmission of Modbus data from these remote devices in JSON format. Other data sources including Allen Bradley, Siemens, OPC, MTConnect and OPTO are also supported. OAS allows you to configure your tag’s data source as JSON and create customizable JSON data packets. A Tag with a JSON Data Source can have a base Structure set directly as a valid JSON string, or it can be set using another Tag. This lets you dynamically modify the base structure, or use the same base structure for multiple tags. Below is an example of editing the JSON structure directly.

Key/tag pairs are then assigned by clicking Add in the table below the Structure property. This opens a Tag browser which allows you to pick a Tag from the local OAS instance or any reachable remote OAS instance. The key is a search parameter defining where to find the JSON node to fill with the Tag value. This key uses JSONPath syntax and can be either a direct path to the node or a dynamic query to find one or more nodes matching the criteria.

Below you can see what the output looks like when subscribing to the tag value in an MQTT client.

For more information on using the OAS JSON Data Source, see our knowledge base article JSON Data Source. Also helpful is this article on JSONPath syntax.

Supported Data Sources