The Siemens SIMATIC RF250R (6GT2821-5AC40) is an ultra-compact HF RFID reader with an RS232 interface operating in ASCII/scan mode. Measuring just 50 × 50 × 30 mm and weighing 14 g, it connects directly to a PC, operator panel, or serial terminal for simple scan-based identification. The reader has no integrated antenna — it connects to an external antenna from the Siemens ANT series (ANT 1, ANT 3, ANT 3NO, ANT 8, ANT 12, ANT 18, ANT 30), allowing the antenna to be positioned independently for optimal transponder reading in space-constrained installations such as tool holders, machine fixtures, and small assembly workstations.

How Does the RS232 ASCII/Scan Mode Operate?

In ASCII/scan mode, the RF250R continuously scans for transponders within the antenna field and outputs detected transponder data as ASCII text over the RS232 serial interface. This mode suits simple identification workflows — for example, a tool management station where an operator presents a tagged tool to the antenna and the reader transmits the tool ID to a PC for tracking. The reader connects via an M12 connector to the serial port and is powered by 24 V DC (20.4–28.8 V) with 50 mA typical current draw.

What RFID Standards and Transponders Are Supported?

The RF250R operates at 13.56 MHz using ISO 15693 and ISO 18000-3 standards. It reads Siemens SIMATIC RF200 transponders including MDS D100, D124, D126, D139, D160, D165, D200, D324, D339, D421, D424, D425, D426, D428, D460, D524, and D528 series. Maximum RF data transfer rate is 26.5 kbit/s. The reader processes one transponder at a time. The achievable read range depends on the selected external antenna and transponder type — typical ranges vary from a few millimeters with small antennas to approximately 65 mm with larger models.

What Are the Installation and Environmental Specifications?

The RF250R measures 50 × 50 × 30 mm and weighs 0.014 kg, allowing installation in extremely tight spaces. It mounts directly on metal surfaces with no minimum clearance. IP65 protection provides complete dust-tight operation and resistance to low-pressure water jets. Operating temperature range is −25 °C to +70 °C. A 3-color LED (green for power/ready, yellow for transponder present, red for error) provides at-a-glance status indication. The reader is RoHS compliant.

Frequently Asked Questions

How does the RS232 variant differ from the IO-Link variant of the RF250R?

The RS232 variant (6GT2821-5AC40) uses ASCII/scan mode for direct point-to-point serial connection to a PC or terminal, suitable for standalone identification stations. The IO-Link variant (6GT2821-5BC32) connects to an IO-Link master for integration into PROFINET/PROFIBUS automation networks with TIA Portal engineering. Choose RS232 for simple, local terminal applications; choose IO-Link for networked automation integration.

Which external antenna should be paired with this reader?

The RF250R supports the full Siemens ANT series. ANT 8 and ANT 12 are compact general-purpose choices. ANT 1 and ANT 3 are slim rod antennas for very tight spaces. ANT 18 and ANT 30 offer extended read range. Refer to the SIMATIC RF200 system manual for detailed antenna dimensions, read range charts, and transponder compatibility matrices.