This article will briefly describe how a PLC works with OPI’s Integris software
Although Integris is a software designed to Monitor temperature and Relative Humidity/Moisture content (HR/MC), ambient conditions (temperature, HR and rain/snow) and to control fans/heaters/chillers either manually or automatically based on OPI’s control algorithms, sometimes because of a customer’s requirements or a special application a PLC is put into the equation. In this case, Integris has been designed to communicate with a PLC via a third-party application: Kepware, which, by the way, requires a license to be purchased.
Through Kepware, Integris can pass all this information (analog and digital inputs and outputs values) on to a PLC. For this purpose, the PLC should be able to communicate with Integris using a communications protocol known as MODBUS.
Kepware software should be installed on the same PC/machine Integris is installed. It will act as a communications bridge between Integris and a PLC. How does this work? The following lines will explain how this works.
- Integris is provided with a feature/functionality (OPC) that publishes tags. These tags are memory registers that contain digital information (digital inputs/outputs) gathered by Integris like:
- Temperature readings from temperature sensors - Inputs
- Relative Humidity readings from moisture sensors - Inputs
- Pressure readings from the Plenum Pressure sensors - Inputs
- Rain/snow detection readings (on/off) - Inputs
- Fan(s) ON/OFF – Outputs
- Heater(s) ON/OFF – Outputs
- Chiller(s) ON/OFF - Outputs
- All the previous information is presented/published (in real time) on memory registers called tags. These registers/Tags are accessible for a PLC via Kepware software, and OPC functionality should be enabled within Integris software to allow this communication between Integris and Kepware.
- Kepware read those registers/tags and pass this information to a PLC via MODBUS communications protocol, so a PLC can either:
- Based on the information received from Integris, execute a customized control action to operate fans, heaters, chillers, or any other control device
- Operate fans, heaters, chillers, or any other control device, based on the Integris control algorithms and control signals (Outputs)