PEX-D24
The PEX-D24 is a direct software and driver-compatible replacement for the ICP DAS PIO-D24 and PIO-D24U series PCI and Universal PCI cards, enabling system integrators to migrate existing automation applications to PCIe platforms without rewriting drivers, modifying software logic or replacing cabling. A 4-bit Card ID SMD switch identifies each card individually in multi-card installations, and four programmable interrupt sources allow interrupt-driven I/O routines to be implemented alongside polled applications without additional hardware.
Key Features
- 24 Bidirectional 5V/TTL Digital I/O Channels — Three 8-Bit Ports: All 24 channels are individually configurable as digital inputs or digital outputs under software control; input threshold is 2.0 V minimum for logic ON and 0.8 V maximum for logic OFF; output sink current is 64 mA at 0.8 V and source current is 32 mA at 2.0 V — capable of directly driving optocoupler inputs, relay coil drivers, and TTL logic without external buffers in the majority of industrial wiring configurations
- 8255 PPI Mode 0 Emulation — Direct Software Migration from PIO-D24: The PEX-D24 emulates two Intel 8255 Programmable Peripheral Interface ports in Mode 0, the same register-level interface used by the legacy PIO-D24 and PIO-D24U cards; existing applications written for those cards — including programmes using ICP DAS DLL libraries, LabVIEW drivers or direct register access — run on the PEX-D24 without modification, eliminating software redevelopment cost during PC chassis upgrades from PCI to PCIe platforms
- 500 kHz Response Speed (~2 μs) on All Channels: Buffered TTL I/O on all 24 channels supports switching frequencies up to 500 kHz, enabling the PEX-D24 to be used in high-frequency pulse counting, encoder feedback reading, stepper motor step/direction control and time-critical relay sequencing applications where response latency below 2 μs is required
- Four Interrupt Sources — Interrupt-Driven I/O Capability: Four independent interrupt sources are available for hardware event notification without continuous polling, reducing CPU overhead in high-channel-count acquisition systems and enabling the host application to respond to edge-triggered external events such as limit switches, proximity sensors and emergency stop signals with deterministic latency
- 4-Bit Card ID SMD Switch — Up to 16 Cards per System: An onboard 4-bit DIP switch assigns a unique Card ID from 0 to 15 to each installed PEX-D24, allowing software to enumerate and address up to 16 cards in a single host PC — expanding total digital I/O capacity to 384 channels (16 × 24) in a single chassis without address conflicts or external multiplexing hardware
- DB37 Connector with Extensive ICP DAS Accessories Ecosystem: The single female DB37 connector is compatible with ICP DAS CA-series shielded cables, DB-series screw-terminal daughter boards and DN-series DIN-rail terminal boards, providing immediate access to field wiring termination without custom cable fabrication; standard accessories cover cable lengths from 30 cm to several metres and support both individual screw-terminal and IDC-connector wiring styles
- Compact PCIe x1 Card — Low Power, Wide OS Support: The PEX-D24 occupies a single PCIe x1 slot at 86 × 134 × 22 mm and draws only 650 mA at +3.3 V with zero current from the +12 V rail, making it compatible with industrial embedded PCs and compact chassis with limited power headroom; the card is supported by ICP DAS Windows driver packages and SDK libraries, and the 8255 register-level interface supports custom driver development under Linux
Application Use Cases
Machine Control and Relay Interfacing
The PEX-D24 controls industrial relay modules, solenoid valve drivers and motor contactor coils directly from PC-based control applications. With sink current of 64 mA per output channel, the card drives standard optocoupler relay module inputs — ICP DAS RLY-series and compatible third-party relay boards — without intermediate transistor buffers. The 500 kHz switching speed supports relay sequencing tasks including conveyor indexing, actuator control and safety interlock switching from a host industrial PC running SCADA or custom HMI software.
PCI-to-PCIe Platform Migration
Industrial PCs based on legacy PCI backplane architectures are progressively being replaced by PCIe-based systems as motherboard manufacturers phase out PCI slots from desktop and embedded platforms. The PEX-D24 is engineered specifically for this transition: it replicates the hardware register interface of the PIO-D24 and PIO-D24U cards at the software level, so existing automation software, DLL-based motion sequences and LabVIEW VIs compiled for those cards execute on the PEX-D24 without modification, reducing system re-qualification effort and extending the operational life of validated control applications.
Automated Test Equipment (ATE)
In automated test and measurement systems, the PEX-D24 controls digital stimulus lines, reads pass/fail signals from device-under-test logic outputs and triggers measurement instruments via interrupt-driven sequencing. The four interrupt sources enable event-driven test execution — for example, starting a measurement on a rising edge from a synchronisation signal — whilst the 500 kHz response speed supports test routines that cycle digital outputs at speeds typical of functional test patterns for logic boards, embedded controllers and relay assemblies.
Multi-Card High-Channel-Count DIO Systems
Applications requiring more than 24 digital channels — machine tool I/O panels, production line signal marshalling, large-format relay logic systems — expand capacity by installing multiple PEX-D24 cards in the same PC. The 4-bit Card ID switch assigns a unique address to each card and ICP DAS driver libraries enumerate all installed cards automatically at initialisation, presenting a unified I/O address space without manual base-address configuration. Up to 16 PEX-D24 cards provide 384 bidirectional TTL channels from a single host chassis.
Signal Monitoring and Digital Data Acquisition
As a 24-channel digital input reader, the PEX-D24 monitors the state of limit switches, proximity sensors, optical barriers, BCD-encoded position indicators and logic-level signals from PLCs and field instruments. The 5V/TTL input thresholds are compatible with the output logic of most industrial sensor families, and the interrupt-driven input mode allows the host application to log signal state changes with edge timestamps without consuming CPU resources in a continuous polling loop — suitable for audit-trail logging, process event recording and fault detection in manufacturing systems.
Why Choose the PEX-D24
Zero Software Changes When Migrating from PIO-D24 or PIO-D24U
The most significant cost in a platform migration is rarely the hardware itself — it is re-validating the software stack. The PEX-D24 eliminates this cost entirely by emulating the 8255 PPI register interface at the hardware level, so the driver model, DLL function calls and register addresses used by PIO-D24 applications remain valid on the PCIe card. For system integrators maintaining validated automation applications in regulated industries, this means a PCIe chassis upgrade can proceed without triggering software re-qualification — the existing software evidence package remains applicable to the replacement platform.
Interrupt-Driven I/O and 500 kHz Response for Real-Time Applications
Polled digital I/O is adequate for slow-moving process control, but applications with sub-millisecond event response requirements — emergency stop detection, encoder edge counting, synchronisation pulse capture — need hardware interrupt capability. The PEX-D24 provides four independent interrupt sources that deliver hardware-level event notification to the host application without relying on the polling interval of a software timer. Combined with the 500 kHz switching speed on all 24 channels, this makes the PEX-D24 suitable for motion control, pulse timing and event-driven test sequences that a polled DIO card cannot reliably support.
Proven ICP DAS Ecosystem — Cables, Terminal Boards and SDK
ICP DAS has supplied compatible accessories for the D24 product family across PCI, Universal PCI and now PCIe generations. CA-series shielded flat cables, DB-series screw-terminal daughter boards and DN-series DIN-rail terminal boards all connect to the PEX-D24's DB37 port without modification, so existing field wiring harnesses and terminal assemblies from PIO-D24 installations are physically reusable on the replacement system. The ICP DAS SDK includes Windows DLL libraries, LabVIEW drivers and code examples for C, C++, Visual Basic and Delphi, covering the majority of industrial HMI and SCADA development environments in use across European manufacturing sites.
Frequently Asked Questions
Is the PEX-D24 software-compatible with the PIO-D24 and PIO-D24U?
Yes. The PEX-D24 emulates the Intel 8255 PPI Mode 0 register interface used by the PIO-D24 and PIO-D24U. Applications that use ICP DAS DLL libraries, LabVIEW drivers or direct register access to the 8255 interface on those cards will run on the PEX-D24 without modification to the application software or driver configuration.
How many digital I/O channels does the PEX-D24 provide?
The PEX-D24 provides 24 bidirectional 5V/TTL digital I/O channels, organised as three 8-bit ports (Port A, Port B and Port C) via a single female DB37 connector. All 24 channels are individually readable as digital inputs or writable as digital outputs under software control.
How many PEX-D24 cards can be installed in a single PC?
Up to 16 PEX-D24 cards can be installed in a single host PC, providing a maximum of 384 bidirectional digital I/O channels. Each card is assigned a unique address using the onboard 4-bit Card ID SMD switch (values 0–15), and the ICP DAS driver software enumerates all installed cards automatically without manual base-address configuration.
What is the maximum switching speed of the PEX-D24's digital I/O channels?
The PEX-D24 supports a maximum switching speed of 500 kHz (approximately 2 μs response time) on all 24 channels. This response speed applies to both digital input reading and digital output switching, making the card suitable for pulse counting, step/direction motor control and other time-critical DIO applications.
What connector and accessories are compatible with the PEX-D24?
The PEX-D24 uses a female DB37 connector. Compatible ICP DAS accessories include CA-series shielded flat cables (in various lengths), DB-series screw-terminal daughter boards for individual channel wiring and DN-series DIN-rail terminal boards for panel-mount field wiring installations. All accessories in the D24 accessory family are interchangeable with those used on the predecessor PIO-D24 and PIO-D24U cards.
The PEX-D24 is a direct software and driver-compatible replacement for the ICP DAS PIO-D24 and PIO-D24U series PCI and Universal PCI cards, enabling system integrators to migrate existing automation applications to PCIe platforms without rewriting drivers, modifying software logic or replacing cabling. A 4-bit Card ID SMD switch identifies each card individually in multi-card installations, and four programmable interrupt sources allow interrupt-driven I/O routines to be implemented alongside polled applications without additional hardware.
Key Features
- 24 Bidirectional 5V/TTL Digital I/O Channels — Three 8-Bit Ports: All 24 channels are individually configurable as digital inputs or digital outputs under software control; input threshold is 2.0 V minimum for logic ON and 0.8 V maximum for logic OFF; output sink current is 64 mA at 0.8 V and source current is 32 mA at 2.0 V — capable of directly driving optocoupler inputs, relay coil drivers, and TTL logic without external buffers in the majority of industrial wiring configurations
- 8255 PPI Mode 0 Emulation — Direct Software Migration from PIO-D24: The PEX-D24 emulates two Intel 8255 Programmable Peripheral Interface ports in Mode 0, the same register-level interface used by the legacy PIO-D24 and PIO-D24U cards; existing applications written for those cards — including programmes using ICP DAS DLL libraries, LabVIEW drivers or direct register access — run on the PEX-D24 without modification, eliminating software redevelopment cost during PC chassis upgrades from PCI to PCIe platforms
- 500 kHz Response Speed (~2 μs) on All Channels: Buffered TTL I/O on all 24 channels supports switching frequencies up to 500 kHz, enabling the PEX-D24 to be used in high-frequency pulse counting, encoder feedback reading, stepper motor step/direction control and time-critical relay sequencing applications where response latency below 2 μs is required
- Four Interrupt Sources — Interrupt-Driven I/O Capability: Four independent interrupt sources are available for hardware event notification without continuous polling, reducing CPU overhead in high-channel-count acquisition systems and enabling the host application to respond to edge-triggered external events such as limit switches, proximity sensors and emergency stop signals with deterministic latency
- 4-Bit Card ID SMD Switch — Up to 16 Cards per System: An onboard 4-bit DIP switch assigns a unique Card ID from 0 to 15 to each installed PEX-D24, allowing software to enumerate and address up to 16 cards in a single host PC — expanding total digital I/O capacity to 384 channels (16 × 24) in a single chassis without address conflicts or external multiplexing hardware
- DB37 Connector with Extensive ICP DAS Accessories Ecosystem: The single female DB37 connector is compatible with ICP DAS CA-series shielded cables, DB-series screw-terminal daughter boards and DN-series DIN-rail terminal boards, providing immediate access to field wiring termination without custom cable fabrication; standard accessories cover cable lengths from 30 cm to several metres and support both individual screw-terminal and IDC-connector wiring styles
- Compact PCIe x1 Card — Low Power, Wide OS Support: The PEX-D24 occupies a single PCIe x1 slot at 86 × 134 × 22 mm and draws only 650 mA at +3.3 V with zero current from the +12 V rail, making it compatible with industrial embedded PCs and compact chassis with limited power headroom; the card is supported by ICP DAS Windows driver packages and SDK libraries, and the 8255 register-level interface supports custom driver development under Linux
Application Use Cases
Machine Control and Relay Interfacing
The PEX-D24 controls industrial relay modules, solenoid valve drivers and motor contactor coils directly from PC-based control applications. With sink current of 64 mA per output channel, the card drives standard optocoupler relay module inputs — ICP DAS RLY-series and compatible third-party relay boards — without intermediate transistor buffers. The 500 kHz switching speed supports relay sequencing tasks including conveyor indexing, actuator control and safety interlock switching from a host industrial PC running SCADA or custom HMI software.
PCI-to-PCIe Platform Migration
Industrial PCs based on legacy PCI backplane architectures are progressively being replaced by PCIe-based systems as motherboard manufacturers phase out PCI slots from desktop and embedded platforms. The PEX-D24 is engineered specifically for this transition: it replicates the hardware register interface of the PIO-D24 and PIO-D24U cards at the software level, so existing automation software, DLL-based motion sequences and LabVIEW VIs compiled for those cards execute on the PEX-D24 without modification, reducing system re-qualification effort and extending the operational life of validated control applications.
Automated Test Equipment (ATE)
In automated test and measurement systems, the PEX-D24 controls digital stimulus lines, reads pass/fail signals from device-under-test logic outputs and triggers measurement instruments via interrupt-driven sequencing. The four interrupt sources enable event-driven test execution — for example, starting a measurement on a rising edge from a synchronisation signal — whilst the 500 kHz response speed supports test routines that cycle digital outputs at speeds typical of functional test patterns for logic boards, embedded controllers and relay assemblies.
Multi-Card High-Channel-Count DIO Systems
Applications requiring more than 24 digital channels — machine tool I/O panels, production line signal marshalling, large-format relay logic systems — expand capacity by installing multiple PEX-D24 cards in the same PC. The 4-bit Card ID switch assigns a unique address to each card and ICP DAS driver libraries enumerate all installed cards automatically at initialisation, presenting a unified I/O address space without manual base-address configuration. Up to 16 PEX-D24 cards provide 384 bidirectional TTL channels from a single host chassis.
Signal Monitoring and Digital Data Acquisition
As a 24-channel digital input reader, the PEX-D24 monitors the state of limit switches, proximity sensors, optical barriers, BCD-encoded position indicators and logic-level signals from PLCs and field instruments. The 5V/TTL input thresholds are compatible with the output logic of most industrial sensor families, and the interrupt-driven input mode allows the host application to log signal state changes with edge timestamps without consuming CPU resources in a continuous polling loop — suitable for audit-trail logging, process event recording and fault detection in manufacturing systems.
Why Choose the PEX-D24
Zero Software Changes When Migrating from PIO-D24 or PIO-D24U
The most significant cost in a platform migration is rarely the hardware itself — it is re-validating the software stack. The PEX-D24 eliminates this cost entirely by emulating the 8255 PPI register interface at the hardware level, so the driver model, DLL function calls and register addresses used by PIO-D24 applications remain valid on the PCIe card. For system integrators maintaining validated automation applications in regulated industries, this means a PCIe chassis upgrade can proceed without triggering software re-qualification — the existing software evidence package remains applicable to the replacement platform.
Interrupt-Driven I/O and 500 kHz Response for Real-Time Applications
Polled digital I/O is adequate for slow-moving process control, but applications with sub-millisecond event response requirements — emergency stop detection, encoder edge counting, synchronisation pulse capture — need hardware interrupt capability. The PEX-D24 provides four independent interrupt sources that deliver hardware-level event notification to the host application without relying on the polling interval of a software timer. Combined with the 500 kHz switching speed on all 24 channels, this makes the PEX-D24 suitable for motion control, pulse timing and event-driven test sequences that a polled DIO card cannot reliably support.
Proven ICP DAS Ecosystem — Cables, Terminal Boards and SDK
ICP DAS has supplied compatible accessories for the D24 product family across PCI, Universal PCI and now PCIe generations. CA-series shielded flat cables, DB-series screw-terminal daughter boards and DN-series DIN-rail terminal boards all connect to the PEX-D24's DB37 port without modification, so existing field wiring harnesses and terminal assemblies from PIO-D24 installations are physically reusable on the replacement system. The ICP DAS SDK includes Windows DLL libraries, LabVIEW drivers and code examples for C, C++, Visual Basic and Delphi, covering the majority of industrial HMI and SCADA development environments in use across European manufacturing sites.
Frequently Asked Questions
Is the PEX-D24 software-compatible with the PIO-D24 and PIO-D24U?
Yes. The PEX-D24 emulates the Intel 8255 PPI Mode 0 register interface used by the PIO-D24 and PIO-D24U. Applications that use ICP DAS DLL libraries, LabVIEW drivers or direct register access to the 8255 interface on those cards will run on the PEX-D24 without modification to the application software or driver configuration.
How many digital I/O channels does the PEX-D24 provide?
The PEX-D24 provides 24 bidirectional 5V/TTL digital I/O channels, organised as three 8-bit ports (Port A, Port B and Port C) via a single female DB37 connector. All 24 channels are individually readable as digital inputs or writable as digital outputs under software control.
How many PEX-D24 cards can be installed in a single PC?
Up to 16 PEX-D24 cards can be installed in a single host PC, providing a maximum of 384 bidirectional digital I/O channels. Each card is assigned a unique address using the onboard 4-bit Card ID SMD switch (values 0–15), and the ICP DAS driver software enumerates all installed cards automatically without manual base-address configuration.
What is the maximum switching speed of the PEX-D24's digital I/O channels?
The PEX-D24 supports a maximum switching speed of 500 kHz (approximately 2 μs response time) on all 24 channels. This response speed applies to both digital input reading and digital output switching, making the card suitable for pulse counting, step/direction motor control and other time-critical DIO applications.
What connector and accessories are compatible with the PEX-D24?
The PEX-D24 uses a female DB37 connector. Compatible ICP DAS accessories include CA-series shielded flat cables (in various lengths), DB-series screw-terminal daughter boards for individual channel wiring and DN-series DIN-rail terminal boards for panel-mount field wiring installations. All accessories in the D24 accessory family are interchangeable with those used on the predecessor PIO-D24 and PIO-D24U cards.
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