Industrial data acquisition devices have been developed at the Department of Control Engineering and Information Technology at the Budapest University of Technology and Economics for many years. These developments resulted a compact and very widely usable device, which is capable of receiving a few analog signals, perform data acquisition tasks or creating large, complex data acquisition systems. This device is called Smart Network Calculator 42, or just SNC-42.
The SNC-42 provide widely usable functions for industrial data acquisition tasks. The device primarily is an 8 channel general usable network data acquisition device in addition it allows for up to three serial line Datarec devices to connect to Ethernet network. It is possible to remote manage these devices with the embedded HTTP server. The server provides data visualization and it allows to modify the device parameters with the use of a simple Web browser. In addition to these functions it provides supervisory functions for the technological personnel with its front panel human machine interface.
The communication abilities of the SNC-42 allows wide usability of the device, but because these solutions are not standardized it makes difficult to connect to other devices provided by different vendors. Another disadvantage is that connection to a FTP server is required to use the stored data, which causes latency in the reception of the values. Because of these facts it became necessary to upgrade its communication abilities, with a widely used industrial protocol which allows direct access to the device’s data. Based on these requirements Modbus TCP protocol was selected. During my developments this semester I implemented a Modbus TCP server into the SNC-42, which now also allows to integrate the device into vendor specific systems.
In the first part of my thesis I present the hardware and software components of the SNC-42 data acquisition device. The next topic will cover the presentation of the Modbus protocol family which is followed by the presentation of the SNC-42 data structures. The next chapter will introduce the implemented Modbus TCP server. In the final chapter I will write about further development possibilities.