The module typically features two sides of pins for interfacing: TTL Side (Connect to Microcontroller) Power input (3.0V - 5.5V). GND: Ground. TXD: Transmit data (connects to MCU RX). RXD: Receive data (connects to MCU TX). RS-232 Side (Connect to PC/Serial Device) VCC/GND: Shared with the TTL side. TXD: RS-232 Transmit. RXD: RS-232 Receive.
The HW-044 datasheet highlights its ability to bridge the gap between high-voltage RS232 signals (up to ±25V) and low-voltage TTL signals (0-5V). Specification MAX3232 (Texas Instruments or similar) Operating Voltage 3.0V – 5.5V DC Baud Rate Support Up to 120 kbps (standard) or 250 kbps TTL Connector 4-pin header (VCC, GND, TX, RX) RS232 Connector Female DB9 (Standard Serial Port) Operating Temp -40°C to +85°C Dimensions ~31mm x 32mm HW-044 Pinout and Interface hw-044 datasheet