Legacy PLCs, CNC machines, and instruments communicate via RS232. The Waveshare RS232 HAT adds a DB9 port to Pi, bridging modern IoT with decades-old hardware.
What is RS232?
RS232 uses +/-12V signalling for noise immunity over cables up to 15 metres. Still used in Indian factories for PLCs, scales, printers, and CNC controllers.
Specs
- MAX3232 transceiver, DB9 male connector
- Up to 230400 bps, UART via GPIO 14/15
- TX, RX, RTS, CTS signals
Wiring
DTE-to-DCE: straight cable. DTE-to-DTE: null modem (TX/RX crossed).
Python Code
import serial
ser = serial.Serial('/dev/ttyS0', 9600, timeout=1)
ser.write(b'READrn')
print(ser.readline().decode().strip())Applications
- Weighing scale integration for inventory management
- PLC data logging via Modbus-over-RS232
- CNC machine monitoring for production tracking
- Barcode printer ZPL/EPL command control
Frequently Asked Questions
Use RS232 and console simultaneously?
No, HAT uses primary UART. Use USB-to-RS232 for second port.
Max cable length?
15m at 9600 baud. Lower baud = further. For longer, use RS485.
Works with Modbus RTU?
Yes, use pymodbus library.
Multiple RS232 devices?
One port per HAT. Use USB-to-RS232 adapters for more.
Conclusion
The RS232 HAT bridges modern Pi IoT with legacy industrial equipment still ubiquitous in Indian factories.
Browse the full Waveshare collection at Zbotic.in with fast shipping across India.
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