The ST-5221 is a specialized remote input/output (I/O) module within the Crevis FnIO S-Series of slice-type system configurations, designed for effective serial communication in industrial applications. This 1-channel module operates with RS-422 protocol and features a comprehensive bus contact design consisting of 8 pins, numbered 0 to 7, along with field power contacts. The pin assignments are as follows: Pin 0 (TxD+), Pin 1 (TxD-), Pin 2 (RxD+), Pin 3 (RxD-), Pin 4 (GND), Pin 5 (GND), Pin 6 (Shield), and Pin 7 (Shield). Status indicators provide real-time feedback, where a green RxD LED signifies received data, while a green TxD LED denotes transmitted data. The module supports ASCII protocol with full duplex transfer capabilities, ensuring efficient data exchange. It includes a spring clamp terminal block for secure connections and supports a baud rate range of 300 to 115,200 bps, accommodating data bit configurations of 7, 8, or 9 bits, with parity options of none, odd, or even and stop bits of either 1 or 2. The ST-5221 exhibits low bit distortion at under 1.6% and accepts valid parameter lengths of 4 bytes. With a total I/O data size of 6 bytes in and 6 bytes out, the RxD buffer is 1024 bytes, while the TxD buffer is 256 bytes. The module operates with a maximum internal power consumption of 155mA at 5 VDC and is rated for an isolation voltage of 1,000 Vrms/Vac. It features a line impedance of 120Ω and measures 99 mm in height, 12 mm in width, and 70 mm in depth, with a maximum cable length of 1 km (twisted pair). The ST-5221 maintains an active lifecycle status, making it a reliable choice for diverse automation needs.