Introduction: A Reliable Choice for Industrial Serial Port Expansion
In the fields of industrial automation, instrument control, and data acquisition, RS-232 serial ports are still many outdated devices PLC、 The preferred communication interface for weighing instruments and modems. As the number of native serial ports on PC motherboards gradually decreases, expanding multiple serial port cards through PCI has become a necessary means. However, industrial sites often face surges, static electricity, and ground loop interference, and ordinary serial port cards are easily damaged or cause communication abnormalities. The ADLINK PCI-1610 series offers a 4-port RS-232 solution, with the PCI-1610CU model integrating 2500VDC isolation and EFT immunity protection, significantly improving system reliability. This article will systematically introduce the engineering selection and application points of PCI-1610 series from model comparison, hardware installation, driver deployment, protection mechanism to troubleshooting, helping engineers make optimal decisions when replacing old multi serial port cards or building new projects.
Model version and selection comparison
The PCI-1610 series covers three main sub models, with differences reflected in bus compatibility, protection level, and connector type:
Model Bus Standard Isolation Protection EFT Protection Connector Size
PCI-1610A PCI 2.1 (5V) No DB37 to 4 × DB25 or 4 × DB9 123 × 92 mm
PCI-1610B PCI 2.1 (5V) without 2500VDC as above
PCI-1610CU Universal PCI 2.2 (3.3V/5V) 2500VDC 2500VDC Same as above 185 × 100 mm (longer)
Selection key:
Modern motherboard compatibility: If the motherboard only provides a 3.3V PCI slot (commonly seen in modern industrial computers), PCI-1610CU (Universal PCI) must be selected; If it is an old-fashioned 5V PCI slot, all three options are available.
Protection against harsh environments: If connecting long-distance outdoor cables or there is a ground potential difference, priority should be given to PCI-1610CU (isolation+EFT); If only connecting short distance devices inside the cabinet, PCI-1610B (EFT only) is also acceptable.
Space limitation: The PCI-1610CU card is longer (185mm), and it is necessary to confirm whether the depth inside the chassis is sufficient; PCI-1610A/B is a short card suitable for compact chassis.
All models come with a 30cm DB37 to 4xDB25 or 4xDB9 branch cable, and users can choose the corresponding ordering option based on the external device interface (such as PCI-1610CU/9 for DB9 version).
Core technical specifications and UART advantages
Communication controller: using 16PCI954 UART with built-in 128 byte FIFO (first in first out buffer). Compared to the traditional 16 byte FIFO of 16550, the large capacity FIFO significantly reduces the number of CPU interrupts, making it particularly suitable for Windows multitasking environments or Linux high load scenarios, effectively preventing data overflow and loss.
Communication parameters:
Baud rate: 50 bps~921.6 kbps (covering regular rates)
Data bits: 5/6/7/8 bits optional
Stop position: 1/1.5/2 bits
Verification: None/Even/Odd
Flow control: hardware RTS/CTS or software Xon/Xoff
Signal line: Complete RS-232 (TxD, RxD, RTS, CTS, DTR, DSR, DCD, RI, GND), supporting modem full signal.
Interrupt and Address: PCI Plug and Play automatically assigns I/O addresses and IRQs without the need for manual jumpers, avoiding resource conflicts. The onboard interrupt status register can accelerate interrupt response speed and improve performance when communicating with multiple ports simultaneously.
Hardware installation and precautions
4.1 Electrostatic protection and card insertion
Turn off the power and open the computer case.
Touching the metal casing releases static electricity.
Select an idle PCI slot (PCI-1610CU, please note if it is a universal slot, usually all PCI slots support 3.3V/5V, but refer to the motherboard manual).
Insert the board, ensure that the golden fingers are fully in place, and secure the baffle with screws.
Connect the branch cable (connect the DB37 end to the board, and connect the other end to the device as needed).
Close the lid and turn on the machine.
4.2 Branch Cable Wiring Instructions
The branch cable converts the DB37 female head into four independent DB9 or DB25 male heads, with each port corresponding to a standard RS-232 serial port (COMx). The default port number is determined by the operating system enumeration order (usually in PCI slot order). If you need to fix the COM number, you can modify the port settings in the Device Manager (Advanced → Port Number).
4.3 Isolation and grounding recommendations (PCI-1610CU only)
The isolation card provides 2500VDC electrical isolation between the PC side and the field side, cutting off the ground loop. But it must be noted that:
The power and signal ground (GND) of the on-site side (external equipment) are completely isolated from the PC side and cannot be directly connected to the two.
If the external device is grounded, it should be ensured that its grounding system does not generate a potential difference with the PC grounding system (the isolation itself has already been subjected to).
If using RS-232 for long distances (>15 meters), it is recommended to reduce the baud rate (≤ 19.2kbps) and use shielded twisted pair cables, with the shielding layer grounded at one end.

Software Drivers and ICOM Tool Suite
5.1 Operating System Support
The PCI-1610 series supports Windows 98/ME/2000/XP Embedded/Vista, as well as Windows CE 5.0/6.0 and Linux. For modern Windows 7/8/10, although not listed on the official list, it is usually possible to install using Windows XP driver compatibility mode (or download updated versions from the ADLINK official website). Built in support for the Linux kernel (using serial or 8250_pci drivers), or using official driver packages.
5.2 ICOM Tools Practical Tools
The ICOM Tools included with the card provide powerful features:
Port configuration: Quickly set baud rate, data bits, flow control, etc.
Port Mapping: Map physical ports to virtual COM numbers.
Diagnostic tool: Loop back test to verify if the port hardware is functioning properly, and send/receive data statistics.
Mode switching: Some models support RS-422/485 (this series only supports RS-232, ICOM Tools is universal but limited in functionality).
5.3 Driver installation steps (Windows)
Insert the driver CD or download the latest driver package.
Run the installation program and select the PCI-1610 series.
The system automatically recognizes new hardware and completes driver loading.
In the Device Manager, four instances of "ADLINK PCI-1610 COM Port" appear under "Ports (COM and LPT)".
Use ICOM Tools for communication testing.
In depth analysis of EFT and isolation protection technology
6.1 EFT (Electrical Fast Transient) Immunity
PCI-1610B and PCI-1610CU are equipped with a built-in 2500VDC EFT suppression circuit, which complies with the IEC 61000-4-4 standard. EFT simulates the pulse train generated by the action of inductive load switches, contactors, etc., which is easily coupled to communication cables. This protection is connected in series on the RS-232 signal line (such as TxD, RxD), and absorbs instantaneous overvoltage through TVS tubes and filtering elements to ensure that the communication chip is not broken down. The common lightning induction and frequency converter interference in engineering belong to this category.
6.2 Isolation Protection (PCI-1610CU only)
Isolation protection adopts optocoupler or magnetic isolation technology to electrically separate the PC side (logic side) from the field side (signal side), with a withstand voltage of 2500VDC. Main advantages:
Eliminating ground loops: When the ground potential difference between PC and equipment reaches tens or even hundreds of volts, non isolated cards can cause signal offset or damage. The isolation card blocks the DC path and greatly attenuates AC interference.
Protection of PC motherboard: Even if there is a short circuit or overvoltage on the on-site side (such as cable misconnection to 220V), the isolation layer can prevent high voltage from entering the PC, ensuring the safety of the entire industrial computer.
6.3 Surge and ESD Protection
All models provide 16kV ESD (electrostatic discharge) protection, in compliance with human body model standards, to avoid contact discharge damage to ports.
Common application scenarios and engineering practices
7.1 Multi PLC/HMI Interconnection
Multiple PLCs in the production line (such as Mitsubishi FX series and Siemens S7-200) communicate with the upper computer through RS-232. Using four ports of PCI-1610CU, each port is connected to a PLC, and the upper computer polls data through Modbus RTU or a custom protocol. Isolation type ensures that the grounding differences of each PLC do not affect communication.
7.2 Instrument Data Collection
All types of digital multimeters, electronic scales, and barcode scanners use RS-232 output. Connect four devices through branch cables and use multi-threaded programs to collect data simultaneously, improving efficiency. Attention: If the device is a 9-pin DCE type, cross cables may be required (but branch cables are standard direct connections and need to be adjusted according to the device type).
7.3 Alternative solutions for industrial serial port servers
In certain situations, multiple serial port cards can be directly embedded into industrial computers to replace external serial port servers, reducing costs and minimizing network latency.
7.4 Replacement of old equipment
If the original system uses an ISA multi serial port card (such as MOXA C168) and the motherboard no longer has an ISA slot, the PCI-1610 series is the ideal upgrade path. The software interface is compatible with standard Windows COM API and does not require rewriting upper layer applications.
Troubleshooting Guide
8.1 The system cannot recognize the board card
Check if the PCI slot is in good contact and perform a slot replacement test.
Confirm that PCI resource allocation (IRQ/IO) is not disabled in the motherboard BIOS.
If it is PCI-1610CU, confirm whether the motherboard PCI slot supports 3.3V (the vast majority supports it, but a few older models only have 5V and cannot work).
Check if there are any unknown devices in the device manager and manually install the drivers.
8.2 Serial communication garbled code or data frame loss
Check the baud rate, data bits, stop bits, and verify if they match the external device.
Confirm that the flow control settings are consistent (if the peripheral uses RTS/CTS, the software must enable hardware flow control).
Reduce the baud rate test. If the low rate is normal, it may be caused by long cables or interference. It is necessary to improve shielding and grounding, or choose an isolated type.
Using ICOM Tools for loopback testing (short circuiting TxD and RxD), the transmitted data should be returned as is, otherwise the port hardware may malfunction.
8.3 Port cannot be opened or occupied
Other applications (such as serial debugging tools, SCADA software) may have occupied the COM number. Close it and try again.
Change the COM number to an idle number (such as COM5~COM8) in the device manager to avoid conflicts with the motherboard's native serial port.
8.4 Communication interruption after triggering EFT protection
If there is strong interference frequently triggering the protection on site, the signal may be briefly clamped and cause errors. Solution:
Use shielded cables and ensure that the shielding layer is grounded at one end.
Add a magnetic ring (ferrite choke) to the cable.
Reduce the baud rate appropriately to increase the anti-interference margin.
8.5 Isolation type card has no output or abnormal voltage level
Confirm that the external device GND is connected to the card field side GND, although isolated, the signal still needs to be referenced to ground.
Measure the on-site TxD to GND voltage, which should be -5~-12V (RS-232 level) when idle. If there is any abnormality, it may cause damage to the isolated power supply and require repair.
Maintenance and environmental recommendations
Temperature range: working from 0~65 ℃, storage from -25~85 ℃, humidity from 5~95% (no condensation). Industrial cabinets need to ensure ventilation and avoid being close to heat sources.
Cleaning: Regularly blow the gold finger and interface with compressed air to prevent oxidation and poor contact.
Cable fixing: Branch cables are relatively thin and should be fixed inside the chassis with zip ties to avoid pulling and damaging the DB37 connector during insertion and removal.
Firmware: There is no user upgradable firmware for this card, and driver updates can be obtained from the ADLINK official website.