ADLINK 7230 Series Isolation DIO Card Selection and Engineering Application Guide

ADLINK 7230 Series Isolation Digital I/O Card Selection and Engineering Application Practical Guide

Why is it necessary to isolate digital I/O? ——The 'safety guard' of industrial sites

In industrial automation, power monitoring, mechanical control, and testing measurement systems, digital I/O (DI/DO) is the most basic and critical signal interface. However, there are often hidden dangers such as common mode voltage, ground loop interference, transient surges, etc. in industrial sites, which can lead to signal misreading in mild cases and controller burnout in severe cases. Therefore, optoelectronic isolation technology has become the first line of defense to protect expensive industrial control hosts.

The 7230 series isolated digital I/O card launched by ADLINK covers various bus forms such as PCI, Low Profile PCI, PCI Express, and CompactPCI, providing 32 isolated inputs and/or outputs. The optocoupler isolation voltage is up to 2500V~5000Vrms, and the output drive current is up to 500mA/channel. It can directly drive relays, solenoid valves, and indicator lights. This article will provide engineers with a complete selection and implementation guide, covering model comparison, electrical characteristics, interruption mechanisms, and wiring techniques.

Quick overview of the entire series of models - choose according to your needs without wasting money

The core differentiation of the 7230 series lies in the input/output direction and bus interface. According to the manual, it can be divided into the following categories:

Model Bus DI Channel DO Channel Isolation Voltage Appearance Special Function

PCI-7230 32-bit PCI 5V 16 5000Vrms standard PCI DI0/DI1 interrupt

PCI-7233 32-bit PCI 5V 320 5000Vrms Standard PCI All Channel COS Interrupt, Input Logic Inverted

PCI-7234 32-bit PCI 5V 0 32 2500Vrms standard PCI Darlington current output

PCI-7234P 32-bit PCI 5V 0 32 2500Vrms Standard PCI Source Current Output (PNP)

LPCI-7230 32-bit PCI 3.3/5V 16 2500Vrms Low Profile DI0/DI1 interrupt

LPCIe-7230 PCIe x1 16 2500Vrms Low Profile DI0/DI1 Interrupt

CPCI-7230 CompactPCI 3U 16 5000Vrms 3U Eurocard DI0/DI1 Interrupt

Key engineering selection points:

Input/output bidirectional → 7230 series (regardless of bus form) is required.

Only 32 inputs are needed, and any changes in one input need to be detected → PCI-7233 (COS interrupt).

Only 32 outputs are needed to drive high current loads → PCI-7234 (current sink) or PCI-7234P (source current, suitable for PNP loads).

The chassis is half height (2U) or PCIe slot → LPCI-7230 or LPCIe-7230.

CompactPCI chassis → cPCI-7230.

Detailed Explanation of Input Characteristics - Wide Voltage, Non Polarity, State Change Interruption

3.1 Input Range and Logic Level (Taking PCI-7230/7233 as an Example)

The isolated input terminal supports non polarity design, which means that regardless of whether it is connected in a positive or negative direction, as long as the voltage difference reaches the threshold, it can be recognized. Input range is 0~24V, logic threshold:

High level (logic 1): Input voltage ≥ 5V (typical)

Low level (logic 0): Input voltage ≤ 1.5V

Input resistance: 1.2k Ω @ 0.5W (approximately) 10mA@12V ， 20mA@24V ）

Engineering meaning: It can be directly connected to 24V DC sensors (such as photoelectric switches, proximity switches) without the need for additional voltage reducing resistors. The non-polar characteristic avoids damage caused by wiring errors.

3.2 Interrupt Trigger Mechanism - Key to Real time Response

3.2.1 7230 series: Channel 0 and 1 edge interruption

PCI-7230/LPCI/LPCIe/cPCI-7230 supports external interrupts for both DI0 and DI1 channels. Users can trigger the rising or falling edge through software settings, which is suitable for signals such as emergency stop buttons, limit switches, encoders Z that require quick response.

3.2.2 7233 Series: Change of State (COS) Interrupt -32 Channel Full Coverage

PCI-7233 is a pure input card, and its biggest highlight is that all 32 channels support state change interrupts. Any change in the level of any channel (high → low or low → high) will immediately generate an interrupt request. This greatly reduces the burden of CPU polling, especially suitable for monitoring a large number of switch states, such as circuit breaker status of distribution cabinets, cabinet door magnets, alarm signals from multiple sensors, etc.

Programming note: COS interrupts require reading the interrupt status register to determine the triggering channel and clearing the interrupt flag, otherwise they will trigger repeatedly.

3.3 Input logic inversion (unique to PCI-7233)

The manual mentions that PCI-7233 has "inverted input logic", which means the input logic is opposite to the usual (high-level input may be read as 0, low-level input as 1). This may be to be compatible with certain "normally closed" sensors (such as NPN type output indicating triggering when low). Before use, it should be carefully tested or logically reversed in the software.

Detailed explanation of output characteristics - balancing driving capability and heat dissipation

4.1 Output type: Darlington transistor (sink current/source current)

The 7230/7234 output adopts a Darlington transistor array, providing high current driving capability. Its output methods are divided into two types:

Sink current: PCI-7234 (and 7230 output side). When the output is logic 1, the output terminal (OUT) conducts to ground (equivalent to NPN transistor saturation), and one end of the external load is connected to the positive power supply, while the other end is connected to the OUT terminal. The current flows from the positive power source → load → OUT → ground, that is, "pours" into the chip.

Source current: PCI-7234P. The output terminal (OUT) is conductive to the positive power supply (equivalent to a PNP transistor), with one end of the load connected to OUT and the other end connected to ground. The current flows from OUT → load → ground, that is, the "source" comes out of the chip.

Selection criteria:

If one end of your load (such as a relay coil) is connected to common ground, it needs to be driven with positive voltage → select the current type (7234).

If one end of the load is already connected to the common positive pole (24V+), it is necessary to use a low-level drive ->select the source current type (7234P).

4.2 Current drive capability and duty cycle limitations (be sure to pay attention!)

The manual provides a very detailed relationship between current and duty cycle, which is a trap that is easily overlooked in engineering design and can lead to chip overheating and damage.

For PCI-7230/7234 (current sink):

Single channel maximum 500mA (100% duty cycle continuous conduction).

But when all 32 channels are simultaneously open:

PCI-7234: The maximum total current is limited to 500mA/channel @ 20% duty cycle (i.e. pulse mode). If it is DC normally open, it needs to be reduced to about 130mA/channel (50% duty cycle) or 370mA/channel (10% duty cycle).

The output side (16 channels) of PCI-7230 is similar, and the manual states: single channel 500mA@100 %When all channels are conducting simultaneously, it is recommended to use 370mA at a 10% duty cycle or 130mA at a 50% duty cycle.

For PCI-7234P (source current):

single channel 500mA@100 %Duty cycle.

When all 32 channels are conducting simultaneously, the total current at a 10% duty cycle is 260mA (i.e. an average of about 8mA per channel), which is much lower than the current sink type because the source current adopts PNP structure, resulting in higher power consumption.

Power consumption budget:

The maximum power consumption of the chip for every 8 DO channels is 1.47W (7230/7234P) or 2.25W (7234).

In engineering, the total power consumption must be calculated based on the actual total current and duty cycle to ensure that it does not exceed the heat dissipation capacity of the board (operating temperature 0~60 ℃).

Practical advice:

If multiple DC relays (coil current of about 30-50mA) need to be driven, 10-20 channels can be turned on simultaneously, but the total power consumption must be calculated. If necessary, external intermediate relays or solid-state relays can be used for expansion to reduce the burden on the board.

For frequent on-off situations (such as PWM control), using pulse mode (low duty cycle) can significantly increase the allowable current.

4.3 Requirements for External Power Supply

Isolation output requires external power supply (5-35VDC), isolated from the PC power supply, provided by the user. Note:

PCI-7230 requires external DC power supply (not just power from PCI).

PCI-7234 has an internal DC-DC converter, but still requires external driving voltage (the manual does not specify whether it is fully self powered, actual wiring needs to refer to pin definitions).

Connectors and Cable Accessories - Quickly Build Test System

According to different bus forms, connectors vary:

Model, connector type, matching terminal board, matching cable

PCI-7230/7233/7234/7234P 37 pin D-sub female head DIN-37D-01 (rail installation), ACLD-9137-01 (universal) ACL-10137-1MM (1 meter, male to male)

LPCI-7230/LPCIe-7230/cPCI-7230 50 pin SCSI-II female head DIN-50S-01 (rail installation) ACL-10250-1 (1 meter, 50 cores)

Wiring prompt:

Use DIN-37D-01 terminal board with clear silk screen markings indicating DI/DO correspondence, and equipped with screw terminals for easy on-site wiring.

For SCSI interfaces, attention should be paid to compact signal arrangement, and it is recommended to use original crimping cables to avoid poor contact.

Software and driver support - worry free across platforms

ADLINK provides a complete driving ecosystem:

Windows: PICS-DASK (traditional) and DAQPilot (new generation recommendation), supporting LabVIEW (DAQPilot for LabVIEW) and MATLAB (DAQ-MTTLB).

Linux：PCIS-DASK/V。

Development languages: VB.net/VC.net/VB/VC++/BBB/Delphi, with accompanying AD Loger data recording software and DAQBench visualization control.

Important reminder: New projects should prioritize using the DAQPilot driver, which provides graphical guidance and a unified API, greatly shortening the development cycle. Although the old version of DASK driver is still available, it is no longer recommended.

Key points of engineering wiring and anti-interference practice

7.1 Input wiring - prevent accidental triggering

Due to the input impedance of 1.2k Ω, for long-distance transmission (>10 meters), it is recommended to use shielded twisted pair cables, with the shielding layer grounded at one end (to the ground at the site).

If the sensor is a dry contact (passive contact), an external pull-up resistor should be connected to 24V (reference input current is about 10-20mA) to ensure a reliable high level when closed.

Non polar input allows reverse connection, but it is recommended to maintain consistent polarity for easy troubleshooting.

7.2 Output wiring - back electromotive force suppression

When driving inductive loads such as relays and solenoid valves, freewheeling diodes (such as 1N4007 or 1N5819) must be connected in reverse parallel at both ends of the load. Otherwise, the induced electromotive force (up to several hundred volts) generated at the moment of shutdown will break through the Darlington transistor, causing permanent damage.

7.3 Power isolation and common ground

The external output power supply (VEXT) should be completely isolated from the digital ground (GND) of the PC host, and the optocoupler should provide an isolation barrier. Do not directly connect the external power ground to the GND of the PC, otherwise it will damage the isolation effect.

If multiple boards share an external power supply, it is necessary to ensure that the power capacity is sufficient (such as 24V/2A or above).

Quick Guide to Interrupt Programming (Based on PCIS-DASK)

Taking the DI0 interrupt of PCI-7230 as an example (code style reference manual example):

Open the device DASK-DevOpen to obtain the device handle.

Set the interrupt trigger edge (rising/falling) through DASK-DI-INt_Start or similar functions (please refer to the DAQPilot API for specific function names).

Register an interrupt callback function, read the input port value in the callback, and clear the interrupt state.

The main program enters a waiting loop and automatically jumps to callback when an interrupt occurs to handle emergency events.

For the COS interrupt of PCI-7233, it is necessary to read the interrupt status register to determine the specific change channel, and then process the corresponding logic.

Troubleshooting and Frequently Asked Questions (FAQ)

Q1: Does the system fail to recognize PCI-7230 after installation?

Check if the PCI slot on the motherboard supports 5V signal (32-bit PCI). Some new motherboards only support 3.3V, so LPCI-7230 (supporting 3.3/5V universal) should be selected. If PCIe is used, LPCIe-7230 must be selected.

Q2: The input status remains high/low regardless of external signals?

Check if the external input voltage is within the range of 5-24V; Check if the COM terminal wiring is correct (non-polar input, but still requires positive and negative connections); Measure the voltage of the input terminal to COM with a multimeter to confirm if the threshold has been reached.

Q3: The output cannot drive the load, even if the program outputs 1?

Confirm that the external power supply (5-35V) has been correctly connected to the power supply terminals of the board (usually VEXT and GND). The Darlington output has an open collector internally and must be connected to an external pull-up resistor or directly connected to the load to the positive power supply (current sink type). If using PCI-7234P source current type, connect one end of the load to OUT and the other end to GND.

Q4: When multiple channels are output simultaneously, does the board heat up severely?

Please check if the total current exceeds the recommended value in the manual. It can reduce the duty cycle (using PWM) or decrease the number of channels conducting simultaneously, and if necessary, install a cooling fan. Long term high temperature will shorten the lifespan of optocouplers.

Q5: Does the COS interrupt of PCI-7233 not trigger?

Confirm that the interrupt enable bit has been correctly set; To confirm whether the input signal edge is clean (jitter may cause multiple triggers), software debounce or hardware RC filtering can be added.