In the fields of industrial automation, data acquisition, and telecommunications equipment, multi port serial communication remains an important way to connect various terminal devices such as modems, data acquisition terminals, and display devices. The CompactPCI (cPCI) platform is widely used in key industries such as transportation, power, and military due to its robust mechanical structure, hot swappable capability, and high reliability. ADLINK cPCI-3534 (4-port, 3xRS-232+1x isolated RS-422/485), cPCI-3544 (4-port fully isolated RS-422/485), and cPCI-3538 (8-port RS-232) serial communication modules are mature solutions that provide high-density and high reliability serial port expansion for these occasions. This article is based on the original user manual and provides a comprehensive technical archive and operation guide for engineers who are still maintaining or creating cPCI serial port systems, covering hardware architecture, pin definitions, jumper configuration, multi card recognition, and multi operating system driver installation.
Product Series Overview and Selection Differences
cPCI-3534、 Both 3538 and 3544 adopt 3U cPCI specifications (160 × 100mm), 32-bit PCI Rev.2.1 bus, support plug and play (IRQ and I/O addresses are automatically allocated by PCI BIOS), and the core serial controller is 16C550A compatible (clock 1.8432~7.3728MHz), with a maximum speed of 115200bps per port. Both are equipped with intelligent buffers (FIFO) to reduce CPU load.
Model Port Configuration Interface Type Isolation Characteristics Maximum Port/System Special Features
CPCI-3534 4-port (A/B/C is RS-232, D is RS-422/485) DIP switch selection only Port D isolation (2500VDC) 8-port (2 cards) supports mixed interfaces
CPCI-3544 4-port full RS-422/485 DIP switch selection, inter channel isolation (500VDC), 32 ports (8 cards), RS-485 automatic direction control
CPCI-3538 8-port full RS-232 pure RS-232 without onboard isolation (optional external C888XB) 16 port (2 cards) high-density standard serial port
Key selection points:
If the on-site equipment mainly consists of standard RS-232 devices (such as old-fashioned modems, industrial computer debugging ports) and requires 8 high-density channels, cPCI-3538 should be selected.
If a small amount of RS-232 is required to be paired with one isolated RS-422/485 (such as connecting remote smart meters), choose cPCI-3534.
If all on-site equipment is RS-422/485 (such as multiple frequency converters, PLCs), and it is required that channels be isolated from each other to avoid ground loop interference, cPCI-3544 should be selected.
If the chassis supports Rear I/O, choose a model with an "R" suffix (such as cPCI-3534R), and use the cPCI-R3534/R3538/R3544 rear board to achieve Rear I/O.
Detailed explanation of hardware interfaces and pin definitions
1. cPCI-3534 (DB37 female head, with 4 ports)
The front panel of the module is equipped with a DB37 female connector, which can be connected to four ports through the accompanying branch cables (C425M with DB25 male connector, or C409M with DB9 male connector).
RS-232 ports (A, B, C) standard signals: TXD, RXD, RTS, CTS, DSR, DTR, DCD, RI, GND, complete 9-wire system, supporting hardware flow control.
Port D (isolated RS-422/485) pin mapping (using DB25 as an example):
Pin 2: TXD+(422) or unused (485)
Pin 3: RXD+(422) or unused (485)
Pin 4: RTS (422) or D+(485)
Pin 5: CTS (422) or D - (485)
Pin 6: RXD - (422 input negative terminal) or unused (485)
Pin 7: Isolated GND
Pin 20: TXD - (422 output negative terminal) or unused (485)
Switching method: Select Port D as RS-422 or RS-485 through the onboard SW1-4 dip switch. At the same time, JP1 (RS-422 terminal resistor) and JP2 (RS-485 terminal resistor) can be enabled with 120 Ω terminal matching through jumper caps, and must be enabled as needed for long-distance communication.
2. cPCI-3544 (DB37 female head, 4-port fully isolated RS-422/485)
Pin allocation is similar to 3534, but all ports are differential signals and each port has an independent isolated ground (rather than shared). Taking DB25 as an example:
Pin 2: TXD+
Pin 3: RXD+
Pin 5: D+(RS-485)
Pin 6: RXD-
Pin 7: This port is isolated from the ground
Pin 8: D - (RS-485)
Pin 20: TXD-
Terminal resistance: Each port corresponds to two sets of jumpers - JP1/JP3/JP5/JP7 for RS-422 terminals, JP2/JP4/JP6/JP8 for RS-485 terminals. Key: The installation of jumper caps enables terminal resistors, which need to be determined based on the length of the cable and the number of nodes.
Multi card recognition: Set the card number (0-7) through the SW1-3 dip switch, supporting up to 8 cards (32 ports), and the card number must be unique.
3. cPCI-3538 (DB62 female, 8-port RS-232)
DB62 leads out 8 channels of full signal RS-232 (TXD, RXD, RTS, CTS, DSR, DTR, DCD, GND), which are connected to external devices through C825M (DB25 branch) or C809M (DB9 branch) cables. Pin allocation is arranged in the order of ports A to H (see Table 1-5 in the manual for details), for example:
Port A: Pin 1=TXD, 2=RXD, 3=RTS, 4=CTS, 5=DSR, 6=DTR, 7=DCD