General
Maximum baud rate	921.6 kbps
FIFO memory	128 Byte
Data bits	5, 6, 7, 8
Insulation	2 kV

The Moxa CP-134U-DB25M is a 4-port universal PCI serial card for industrial automation applications, enabling PC-based data acquisition over long distances and in multi-point networks. The card is designed for use in environments where reliable, high-speed serial communication is required, such as in process automation, machine control, or building automation. It offers four serial interfaces, supporting RS-232, RS-422, or RS-485 depending on configuration, with the first two ports additionally providing RS-232 functionality. The card is available for operation in standard and wide-temperature environments, with the wide-temperature version designed for operating temperatures from -40 to 85 °C.

Applications

The CP-134U-DB25M is suitable for applications requiring communication with multiple serial devices over a common network, such as in industrial control systems or communication with sensors, actuators, or industrial control devices. The RS-485 multidrop function enables connection of up to 31 devices in a daisy chain over a distance of up to 1.2 km. The card is therefore ideal for decentralized systems where central control is exercised over multiple remote end devices.

Features and Equipment in Detail

The card features a 128-byte FIFO buffer, which accelerates data transfer and reduces CPU utilization. The integrated hardware and software flow control (RTS/CTS, XON/XOFF) ensures stable data transmission, especially at high data rates. The maximum baud rate is 921.6 kbps, enabling high data transfer performance. The card supports various data formats, including 5, 6, 7, or 8 data bits, 1, 1.5, or 2 stop bits, and parity types such as None, Even, Odd, Space, and Mark. The serial signals include TxD, RxD, RTS, CTS, DTR, DSR, DCD, and GND for RS-232, as well as Tx+, Tx-, Rx+, Rx-, and GND for RS-422/485. For RS-485 2-wire connections, Data+ and Data- signals are supported.

Technology Explained Simply

A central feature of the card is the integrated ADDC® technology (Automatic Data Direction Control), which automatically manages data direction during RS-485 communication. This relieves software development, as no manual control of transceiver enable signals is required. The card is based on the Moxa Turbo Serial Engine™ chip with a MU860 controller, compatible with the 16C550C standard. The serial ports are connected via a DB44 connector, and the card is designed for 32-bit universal PCI bus systems. Power supply is via the PCI bus at 5 V DC; the standard version consumes 180 mA, while the isolated version (CP-134U-I) consumes 850 mA.

Compatibility and Accessories

The card is compatible with 3.3 V and 5 V PCI as well as PCI-X bus systems. For software integration, drivers are available for a wide range of operating systems, including Windows (including Embedded and Server versions), various Linux kernel versions (2.4.x to 5.x), and UNIX systems such as QNX 6, SCO OpenServer, UnixWare 7, Solaris 10, and FreeBSD. The card can be installed up to eight times in a single PC, achieving high scalability. The package includes a cable with M44 connector to four DB9-M connectors (50 cm), enabling connection to standard 9-pin serial devices.

Installation and Mounting

Installation is performed by inserting the card into a free PCI slot of the computer. The card is designed as a semiconductor card and is connected to the PCI bus for power and data. The connection interface (DB44) enables connection to external serial devices. Integrated LED indicators (Tx, Rx) for each port allow visual monitoring of data transmission. The card requires no additional power supplies or external controls.

Operational Advantages

The high data rate of up to 921.6 kbps and the 128-byte FIFO storage ensure efficient data transfer with low CPU load. The ADDC® function simplifies RS-485 communication, as no additional software control of data direction is required. Support for multiple operating systems and high scalability (up to eight cards per PC) make the card highly flexible. The wide-temperature version enables use in extreme environments, while the 2-kV isolation (on CP-134U-I) provides protection against electrical interference. The card complies with standards EN 55032/35, CISPR 32, FCC Part 15B Class B, as well as IEC 61000-4-2 and -4-3. The MTBF is 480,209 hours, indicating high reliability. The warranty period is five years.