Modbus support in CSWorks

Author: Sergey Sorokin

Published: 2012-02-27 23:51:00

Last update: 2013-09-02 19:29:52

Tags: hmi
scada
modbus
thermostat
netbiter
integration
temco

Slug: Modbus-support-in-CSWorks

Starting from version 2.1, CSWorks installation package includes Modbus TCP data source provider. Now you can build web-based solutions that can communicate with Modbus devices - controllers, modules, thermostats - any kind of hardware that supports Modbus. Here is a quick demonstration.

Hardware

We will need:

• room thermostat that supports Modbus RTU (in this demo we use Tstat6 thermostat provided by Temco Controls);
• Modbus TCP to serial adapter;
• local network;
• desktop computer (server);
• notebook computer (client).

We have to use Modbus TCP to serial adapter, because CSWorks supports only TCP version of the Modbus protocol, and our thermostat provides only Modbus RTU (good old RS-485) connectivity. Make sure that:

• both computers and Modbus adapter are connected to your local network;
• thermostat is connected to the adapter via RS-485.

Software

The following software will be used:

• CSWorks 2.1 on the server; full CSWorks version is required, CSWorks Light will not let clients from other computers access the application;
• Microsoft VisualStudio 2010 on the server;
• web browser on the notebook.

Build demo application

On the server computer, open VisualStudio project at C:\Program Files\CSWorks\Demo\Src\ModbusThermostatIntegrationDemo\ and build it. Please note that these connection points used in this sample are specific to the particular thermostat, your connections points will be different - see Modbus integration guide for your thermostat. Build Release|x86 (for 32-bit installations) or Release|x64 (for 64-bit installations) configuration. Build script will place the compiled application file (CSWorks.Client.ModbusThermostatIntegrationDemo.xap) and hosting HTML file (ModbusThermostatIntegrationDemo.html) to the correspondent locations under C:\Program Files\CSWorks\Demo\Web\. Your client demo application is ready.

Add LiveData source

CSWorks LiveData Service must be aware of the new data source - Modbus device. Our client application will connect to a data source called "Tstat6" (see MainPage.xaml of the client application), so we have to add a new data source with this name. Add the following piece to the LiveData Service configuration file (see C:\Program Files\CSWorks\Framework\Server\CSWorks.Server.LiveDataService.exe.config):

<modbusTcpLiveDataSource name="Tstat6" ipPort="502" ipAddress="192.168.1.71" unitId="254" sampleBufferLength="16" updateRate="500">
  <templates>
    <template name="analogOutputHoldingRegisterInt16" type="Int16" readPath="AnalogOutputHoldingRegister(($address))" canWrite="true" />
  </templates>
</modbusTcpLiveDataSource>

This demo works only with Analog Output Holding Registers, so there is only one template is defined for this data source. Please make sure that unitId attribute corresponds to the device identifier of the thermostat, otherwise CSWorks may not be able to communicate to it. When done, restart CSWorks LiveData Service.

Configure LiveData web service

LiveData web service must be aware of the "Tstat6" data source as well. Add an antry for "Tstat6" to the LiveData Web Service configuration file (C:\Program Files\CSWorks\Demo\Web\LiveDataWebService\web.config):

<liveDataTopology>
  <liveDataPartitions>
    <liveDataPartition name="partition1" primaryLiveDataServer="liveDataServer_1_primary" secondaryLiveDataServer="">
       <dataSources>
         ...
         <dataSource name="Tstat6"/>

Run the application

On the client notebook, open a browser and navigate to the CSWorks application page:

http://<server_computer_name_or_ip_address>/CSWorksDemo/ModbusThermostatIntegrationDemo.html

After a few seconds of initialization, you will see the demo reading values from the thermostat (click on the image to enlarge it):

Congratulations! Your thermostat is web-enabled now.