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

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.