General
Number of ports	4
Data bits	5, 6, 7, 8
Stop bits	1, 1.5, 2

The Moxa CB-134I is an industrial-grade, 4-port RS-422/RS-485 module in PC/104-Plus format, designed for serial data transmission in demanding embedded systems. It is particularly suitable for applications in automation technology, where reliable and interference-protected communication via serial interfaces is required. The modules feature galvanic isolation of 2 kV, protecting them against electrical interference and potential differences, and enhancing operational safety in industrial environments. The interfaces are configurable per port via DIP switches, allowing selection between RS-422 and RS-485 (2-wire or 4-wire) according to requirements.

Applications

The CB-134I is used in systems requiring robust serial communication, such as in process automation, machine control, power supply technology, or transportation technology. Support for wide temperature range from -40 to 85 °C makes the module suitable for use in extreme environments, such as outdoor installations or industrial facilities with high thermal loads. PC/104-Plus compatibility enables integration into compact, modular systems, often used in embedded computers or industrial controllers.

Functions and Features in Detail

Each of the four ports features a 128-byte FIFO buffer, which enhances data transmission efficiency by reducing CPU load and preventing buffer overflows. The maximum baud rate is 921.6 kbps, with support for non-standard transmission rates as well. Flow control is implemented via software (XON/XOFF), enabling simple control of data transmission. For diagnostics and monitoring, each port includes LEDs for transmit (Tx) and receive (Rx), visually indicating the operational status. IRQ and I/O addresses are automatically assigned via BIOS, simplifying system integration.

Technology Explained Simply

The 2 kV galvanic isolation protects the module’s internal circuits from voltage spikes and electrical interference caused by differing ground potentials or inductive noise. The RS-422 interface enables bidirectional, full-duplex communication over 4-wire lines, while RS-485 is suitable for half-duplex or multidrop configurations over 2-wire lines. DIP switches allow hardware-based configuration of the interface type without requiring software changes. FIFO buffers ensure that data packets are not lost even during brief CPU load peaks.

Compatibility and Accessories

The module is compatible with operating systems such as Windows XP, Vista, 7, CE 5.0/6.0, and XP Embedded. System integration is achieved via the PC/104-Plus bus (PCI), with connection through a 40-pin box header. Optional DB9 and DB25 interface cables are available, enabling connection to standard serial devices. The maximum number of CB-134I modules per PC is eight, allowing scalable expansion of serial interfaces.

Mounting and Installation

Installation is performed by inserting the module into a PC/104-Plus system, where it is directly plugged onto the 40-pin box header. Interface configuration is done via DIP switches on the module. BIOS-controlled assignment of IRQ and I/O address simplifies installation, as no manual configuration is required. The module is installed without additional tools, as it is mechanically inserted directly into the system.

Operational Advantages

The combination of galvanic isolation, FIFO buffers, and automatic address assignment ensures high operational reliability and easy integration. Support for wide temperature range extends the application range in harsh environments. Integrated LEDs enable quick visual diagnostics, and compatibility with various operating systems increases flexibility in system selection. The module format in PC/104-Plus format enables a compact and modular system architecture, well-suited for integration into embedded systems.