ADLINK PCI-7250 Series Relay Output and Isolation Input Card Configuration and Protection Circuit Guide

In industrial automation control systems, the on/off control of relays and reliable acquisition of external switch signals are the most fundamental and critical requirements. Whether driving high-power contactors, controlling solenoid valves, or monitoring limit switch status, I/O cards are required to provide sufficient driving capability, electrical isolation, and anti-interference performance. ADLINK PCI-7250 series relay output and isolation digital input card provides 8 relay outputs (including Form C and Form A types) and 8 optocoupler isolated inputs, supports AC/DC signal access, can select AC filtering or non filtering mode through jumper, and is equipped with onboard LED to indicate relay status. This series covers multiple bus specifications including PCI, CompactPCI, Low profile PCI, and PCI Express, and can flexibly adapt to various industrial control platforms. This article will systematically explain the engineering application points of the PCI-7250 series from hardware configuration, pin definition, register programming, relay protection circuit to software support.

Product Family and Core Features

The PCI-7250 series includes the following models:

PCI-7250: Standard PCI specification, 8 relay outputs (R0~R3 are Form C, R4~R7 are Form A)+8 optocoupler isolated inputs, onboard LED indicates relay status.

PCI-7251: The expansion board of PCI-7250 provides an additional 8 relay outputs (all Form C) and 8 isolated inputs per board, with a maximum of 3 boards mounted, expanding the total number of channels to 32.

CPCI-7252: CompactPCI 3U specification, 8 relay outputs (all Form C)+16 isolated inputs, suitable for high-density rack mounted systems.

LPCI-7250: Low profile PCI specification, 8 relay outputs (all Form C)+8 isolated inputs, suitable for compact chassis.

LPCIe-7250: PCI Express x1 specification, with 8 relay outputs (all Form C) and 8 isolated inputs, suitable for modern motherboards without PCI slots.

All models adopt optoelectronic isolation technology (with a maximum isolation voltage of 5000Vrms) to completely isolate the on-site side from the PC ground, effectively suppressing common mode interference and surge impact. Rated capacity of relay contacts: AC 120V@0.5A Or DC 24V@1A (Partial models DC) 30V@2A ）It can directly drive small and medium-sized loads.

Hardware installation and jumper configuration

2.1 Unpacking and Anti static Treatment

The board is an electrostatic sensitive device and must be operated on an anti-static workbench, wearing a grounding wristband. Check the contents of the packaging: main card, ADLINK CD, software installation guide, and this manual. If there are any missing or damaged items, please contact the dealer.

2.2 Jumper Setting (AC Filter Selection)

PCI-7250/7251, LPCI-7250, and LPCIe-7250 are equipped with 8 sets of jumper wires, JP1~JP8, corresponding to DI0~DI7, respectively, used to select whether the input signal has undergone AC filtering:

Jumper corresponding channel function

JP1~JP8 DI0~DI7 1-2: AC filtering (AC signal, filtering out 50/60Hz noise)

2-3: Non AC filtering (DC signal, default)

Selection suggestion: If the input signal is an AC powered sensor (such as an AC proximity switch), it is recommended to enable AC filtering to eliminate false triggering caused by power frequency interference; If it is a DC signal (24VDC switch), use non AC filtering mode to obtain the fastest response speed.

2.3 PCI/PCIe slot installation

Turn off the power of the computer and all peripherals, and remove the chassis cover.

Select an idle PCI/PCIe slot, align the board and insert it, ensuring that the gold fingers are fully in contact, and secure the baffle with screws.

For cPCI-7252, insert it into the I/O slot of the CompactPCI chassis.

2.4 External connector (CN1)

The pin definitions for different models vary, please refer to Tables 2-3 to 2-5 in the manual for details. Taking PCI-7250 as an example:

Relay terminals: Each relay provides three terminals (Form C): COM (common), NO (normally open), and NC (normally closed), or COM+NO (Form A).

Digital input: DI0~DI7 are input signal terminals, IGND is common ground. Input does not need to distinguish polarity (optocoupler bidirectional), both AC and DC are acceptable.

PCI-7251 Expansion Connection: Connect PCI-7250 to PCI-7251 via a flat cable, with up to 3 expansion boards, automatically recognized by the system. The register mapping of the expansion board is from Base+2 to Base+7.

Register Mapping and Low Level Programming

The PCI-7250 series uses the PLX PCI-9050 bridge chip, and the system BIOS automatically assigns I/O base addresses. The base address can be read by offsetting the PCI configuration space by 18h. All registers are 8-bit.

3.1 PCI-7250 (including extensions) Address Mapping

Offset (hexadecimal) write operation, read operation corresponding to the card

0x00 relay output reads back to PCI-7250 motherboard

0x01 Unused isolated input PCI-7250 motherboard

0x02 Relay output readback PCI-7251 # 1

0x03 Unused isolated input PCI-7251 # 1

0x04~0x07 Same as above PCI-7251 # 2/# 3

3.2 cPCI-7252 Address Mapping

Offset write operation read operation

0x00 relay output isolation input (low 8 bits)

0x01 Unused isolated input (high 8 bits)

0x02 Unused output readback

3.3 LPCI/LPCIe-7250 Address Mapping

Offset write operation read operation

0x00 relay output read back

0x01 Isolation input not used

3.4 Register Data Format

Relay output register (write): Each bit controls one relay, 1=engage, 0=release. The initial state is all 0 (released).

Output Read Back Register (Read): Returns the actual state of the relay, 1=engaged (normally open closed), 0=released.

Isolation input register (read): returns the external input level status, 1=input high (3~24V), 0=input low (0~1.5V).

3.5 Programming Example (C Language)

#include <dos.h>

#include <conio.h>

#Define BASE 0x300//Assuming base address

//Output control

outportb(BASE + 0x00, 0x0F); //Absorb R0~R3 and release R4~R7

//Read back output

unsigned char status = inportb(BASE + 0x00);

//Read input

unsigned char input = inportb(BASE + 0x01);

Relay selection and contact protection circuit

4.1 Difference between Form C and Form A Relays

Form C (conversion type): three terminal COM, NO, NC. When control bit=1, COM and NO are connected; =At 0:00, COM and NC are connected. Suitable for scenarios that require switching between two loads (such as motor forward and reverse rotation).

Form A (normally open): Two terminal COM, NO. When the control bit is set to 1, it conducts; when it is set to 0, it disconnects. R4-R7 of PCI-7250 are Form A, while all other models are Form C.

4.2 Load capacity and lifespan

PCI-7250/7251/cPCI-7252：AC  120V@0.5A ， DC  24V@1A Mechanical lifespan>5 × 10 ⁵ times (resistive load).

LPCI/LPCIe-7250：DC  30V@2A Life>10 ⁵ cycles (2A load).

Important reminder: Inductive loads (motors, solenoid valves, contactor coils) may generate reverse induced electromotive force when power is cut off, which may cause breakdown of relay contacts or shorten their lifespan. A protective circuit must be added!

4.3 Common protection circuits (see manual appendix)

Characteristics of applicable scenarios for protective circuits

RC absorption circuit AC/DC load R=0.5~1 Ω/V (contact voltage), C=0.5~1 μ F/A (contact current). Can suppress sparks, but leakage current may cause timer misoperation

The diode continuous current DC load diode is connected in reverse parallel at both ends of the load, which prolongs the release time and significantly improves the protection effect. Select diodes with reverse withstand voltage ≥ 10 times the power supply voltage and forward current ≥ load current

A DC load consisting of a diode and a Zener diode connected in series can accelerate the release time, and the Zener voltage is approximately equal to the power supply voltage

Varistor AC/DC loads utilize nonlinear resistance characteristics to clamp overvoltage, with fast response speed and suitable for high-energy surge applications

Wiring method: The protective device should be connected across the load terminals (rather than the relay contacts) to absorb the back electromotive force generated by the load.

Key points for using isolated digital inputs

5.1 Input Characteristics

Input voltage range: 3~24V AC/DC (logic high), 0~1.5V is logic low.

Input current: rated 10mA, maximum 60mA.

Input impedance: 2.2k Ω (built-in current limiting resistor).

Isolation voltage: PCI-7250/7251/cPCI-7252 is 5000Vrms; LPCI/LPCIe is 2500Vrms.

5.2 High Voltage Input Expansion

If a 110V AC/DC signal needs to be connected, it can be achieved by replacing the upper limit current resistor Ri (default 1.2k Ω) on the board. Calculation formula:

text

Ri=Vin/0.01 (A)//Set current to 10mA

Pw=Vin × 0.01 (W)//Resistance power

For example, when Vin=110V, Ri=11k Ω, power=1.1W. It is recommended to use a metal film resistor with sufficient margin.

5.3 AC filtering mode

When the input is an AC signal (such as a power frequency proximity switch), it is recommended to set the corresponding jumper to an AC filter (1-2). The built-in RC filter (with a time constant of about 5ms) can effectively remove 50/60Hz noise and prevent high-frequency jitter from causing misreading. If it is a pure DC signal, set it as non AC filtering (2-3) to obtain the fastest response.

5.4 Input Wiring

PCI-7250: Connect the DI terminal to the signal positive/live wire, and connect the IGND terminal to the signal negative/neutral wire. The optocoupler is a bidirectional structure with interchangeable polarities.

DI8~DI15 of cPCI-7252: adopts independent differential input, also without polarity differentiation.

Software Drivers and Development Environment

ADLINK provides comprehensive software support for the PCI-7250 series:

6.1 New generation driver: DAQPilot

ADLINK recommends all new users to use DAQPilot driver/SDK, providing a unified API, graphical interface, ActiveX, and more NET assembly, supports rapid development. It can be downloaded for free from the ADLINK official website.

6.2 Classic Driver: PCIS-DASK

32-bit kernel driver for Windows Vista/XP/2000, supporting languages such as C/C++, VB, Delphi, etc. For LPCI/LPCIe-7250, PCIS-DASK (including L-version driver) must be used. DASK/X is a Linux version.

6.3 Third party software support

LabVIEW: DAQ-VIEW PnP VI library, consistent with NI DAQ VIs style.

MATLAB: DAQ-MTLBB adapter, supporting Data Acquisition Toolbox.

Agilent VEE: PICS-VEE User Object Library.

ActiveX/DAQBench: A control package for SCADA/HMI.

DAQCreator: Non programming data acquisition software that supports data recording and FFT analysis.

6.4 Basic Programming Process (PCIS-DASK)

#include <Acl_pci.h>

U16 cardNo, existCards;

//Initialization (DASK style)

if (DASK_Initial(&existCards) ! = SUCCESS) return;

cardNo = 0;

//Relay output (low 4 position engagement)

DASK_DO(cardNo, 0x0F);

//Read isolated input

U16 diVal;

DASK_DI(cardNo, &diVal);

Typical application scenarios and troubleshooting

Key points and precautions for wiring in application scenarios

Drive the contact of the AC contactor relay to the contactor coil, and parallel connect the RC absorption circuit at both ends of the coil. The contactor coil is a strong inductive load and must be protected, otherwise the contact life will be greatly reduced

Read button/limit switch DI connected to one end of the switch, IGND connected to the other end (or common ground). If the input line is long (>10m), it is recommended to enable AC filtering or use shielded wire

Extended Multi Output (3 PCI-7251) Flat Cable Connect PCI-7250 to each expansion board, with automatic address allocation for each expansion board, up to 32 outputs and 32 inputs

Check whether the AC proximity switch DI is connected to the output, IGND is connected to the negative power supply, and the jumper is set to AC filtering. Pay attention to whether the switch output is AC or DC. AC filtering will introduce a delay of about 5ms

Possible causes and solutions for the fault phenomenon

The relay does not engage and the control position is not written correctly; Insufficient driving current; Check if the I/O address is correct when the relay coil is open circuited; Measure whether the+5V power supply of the board is normal; Measure the coil resistance with a multimeter (approximately 150 Ω)

Contact adhesion or erosion of inductive loads without protection; Install RC/diode protection when the load current exceeds the limit; Replace with an external relay with a higher rated current

The input status is always 0, and the input voltage is too low; Wiring error; The optocoupler is damaged and the voltage between DI and IGND is measured (≥ 3V is considered high); Check if the public end is connected

The input state jumping signal has jitter or power frequency interference; Improper setting of filter jumper to enable AC filtering; Increase input capacitance; Add debounce delay in software

The system cannot recognize poor contact in the PCI slot of the board; Resource conflict re plugging; Adjust PCI resources in BIOS; Attempt to replace the slot

Invalid expansion board, flat cable not connected or connection sequence incorrect. Confirm cable connection is secure; Connect PCI-7251 in order from near to far

Selection suggestions and upgrade path

Newly installed industrial computer (without PCI slot): Choose LPCIe-7250, PCIe x1 interface, compatible with modern motherboards.

Compact chassis: Choose LPCI-7250 (Low profile) to save space.

High density rack system: Choose cPCI-7252, support 16 inputs, suitable for CompactPCI platform.

More than 8 channels required: Purchase PCI-7250+up to 3 PCI-7251 to achieve 32 outputs and 32 inputs without the need for additional slots.

Driver selection: DAQPilot is recommended for new projects, and PCIS-DASK (compatible with Windows Vista 64 bit) will continue to be used for upgrading old systems.