Overview:
For the H6 series of products, which includes two DB-9pin serial ports by default, the default operating mode is RS232. These two ports support three modes of operation: RS232, RS422, and RS485. Users can choose the desired mode according to their needs. The following outlines the method for switching modes.
I. Selecting COM Mode in BIOS:
1-1. Press the power button and quickly tap the Del key on the keyboard to enter the BIOS. Navigate to Advanced > SIO MISC Configuration. In the COM1 Mode and COM2 Mode settings, users can select their desired operating mode: RS232 (default), RS485, or RS422, based on their requirements.
1-2. When the configuration is complete, press the keyboard F10 key to save and exit.
II. Pin Definitions for RS232, RS485, and RS422: Note: Different operating modes have different pin definitions for the DB-9pin COM ports. Please connect external devices according to the operating mode and pin definitions.
2-1. RS232 is defined as follows:
2-2. RS485 is defined as follows:
2-3. RS422 is defined as follows:
III. Characteristics of RS232, RS485, and RS422:
RS232:
- Maximum transmission rate: 20kbps
- Maximum communication distance: 15 meters
- Transmission requires three wires: RX, TX, and GND
- When in use, RX needs to be connected to TX in a crossover configuration
- RS232 uses negative logic levels with a range of ±15V
RS485:
- Evolved from RS232, RS485 utilizes half-duplex transmission
- Similar to RS422, it employs balanced transmission
- Transmission rate: 10Mb/s
- Communication distance: up to 1200 meters
- Typically consists of two wires: A (RS485+) and B (RS485-)
- Uses differential signal negative logic; +2V to +6V represents "0", while -6V to -2V represents "1"
RS422:
- Defines a balanced communication interface
- Utilizes twisted pair transmission
- Transmission rate: 10Mb/s
- Communication distance: up to 1200 meters
- RS422 consists of R+, R-, T+, T-, and GND
- When in use, R+ and T+ form one pair, while R- and T- form another pair
