Modbus Filtering & Data Extraction on Comtrol’s DeviceMaster UP with Modbus TCP

There are many questions to answer when interfacing a device to an RFID reader; it can be overwhelming for even the most experienced PLC programmers. Like most of us, you probably have limited time and budget to finish the task.

How do you format the RFID tag data? How do you extract the company, product, and serial number parameters from the many possible bit encoded formats? How do you filter out repeated data? How do you handle data from different antennas on the same RFID reader? What if you also need to verify that RFID and barcode data match correctly? How do you possibly do it all in ladder logic?

Comtrol provides a solution with its patent-pending Filtering and Data Extraction process. This user-friendly and highly configurable process greatly simplifies PLC programming while doing the hard work so the PLC doesn’t have to. What does this technology do?

  • Extracts the company, product, and serial numbers from all 43 EPCglobal RFID tag formats.
  • Extracts the company and product codes from EPC/EAN barcodes.
  • Provides highly programmable filtering of string, RFID tag and barcode data. Data is aged so the PLC gets only the data it needs and when it needs it.
  • Provides the RFID and Barcode parameters to the PLC in a simplified and easy-to-use format.
  • With the peer-to-peer Modbus TCP functionality, polling for data is optional The gateway or proxy can write the data directly into PLC memory pace.

Patent-pending DualConnect technology allows you to send the data to both the PLC and an application so your IT department can receive the data too.

One example of the technology at work is a conveyor installation, where containers may be received with multiple devices. Each has an RFID tag and both a PLC and database require the tag data. The system allows the PLC to receive the tag parameters just once to divert the container correctly. At the same time, a database application can receive all the tags to maintain inventory control.

Both a barcode and an RFID tag must be attached to each container and they both must be correct. The parameters for both the RFID tag and barcode can be extracted and placed directly into PLC memory. The PLC program need only perform simple compares to verify the RFID and barcode data.

In this environment, a device such as a high-speed servo or encoder sends out status data continuously. The string filtering option filters out duplicate status data so the PLC only receives the status data when it changes.