All PLCs and mini-PLCs are very similar in terms of function, hardware, operation, design, etc., which makes them pretty interchangeable and universal devices. The most distinguishing aspect of such devices is programming software. That is why the user has to immerse themselves in learning the programming environment to program the device at hand. Sometimes, it is quite a time-consuming effort. To save your time, we decided to provide you with various sample projects on programming our programmable relay PR200. Our ultimate objective is to create as many such projects as needed to cover the whole functionality of programming environment akYtec ALP.

As reported by our technical support group, the most frequently asked questions on PR200 and akYtec ALP are about the processing of analog inputs and using the RS485 interface. Drawing on this, we have decided to dedicate our first sample project exactly to this topic.

There are many ways to utilize analog inputs of a PLC in industrial automation, HVAC or agriculture. One of the most common is monitoring of temperature and humidity. For this purpose, akYtec GmbH offers the following devices:

  • - Temperature sensor DTS125L
  • - Temperature transmitters NPT1 and NPT3
  • - Humidity and temperature transmitters PVT10 and PVT100

For this sample project, we choose two temperature sensors – DTS125L-PT100 and DTS125L-PT1000 – to receive temperature signals and draw your attention to the settings of configurable analog inputs (4-20 mA, 0-10 V or 0-4000 ohm). The PT1000 is connected directly. We simply set an analog input of PR200 for 0…4000 ohm and utilize a ready-to-use macro Pt1000 from Online Macro Database. It could be proceeded the same way with the PT100, but for a negative effect on the signal accuracy. To resolve the matter, we connect our PT100 sensor through temperature transmitter NPT1. The NPT1 converts the signal of the sensor into the signal of 4-20 mA, so it could be easily read by another analog input of the programmable relay PR200.

The programmable relay PR200 from akYtec is available in many variants depending on the supply voltage, the number of the RS485 interfaces and I/O-points. Since this project requires two RS485 interfaces and an output 4-20 mA, the PR200-24.2.2 fits here most. This programmable relay is powered by 24 V DC and features four analog inputs, two analog outputs 4-20 mA and two RS485 interfaces.

The humidity and temperature transmitter PVT100 has been chosen for humidity measurement. This device can be connected whether to another analog input or to an RS485 interface. We prefer the second option in order to guide you through the Modbus settings in the akYtec ALP. The other RS485 interface we apply to output the data from the temperature sensor PT100 and display them on the RS485 display SMI2. The value of humidity is displayed on the ITP11 process display that is connected to one of the analog outputs of our compact PLC.

The intelligent relay PR200 features a 2-line 32-character LCD display. To familiarize you with programming the display of this device, we bring out for display the data from all connected sensors.

programmable relay

The project file and its detailed description you can find on the product page of the PR200 programmable relay > Product description > Sample project.