Product Description
Industrial signal-conditioning subassembly that bridges 24VDC signals to Raspberry Pi GPIO. The GS-500 level-shifts six industrial 24VDC signals to 3.3V GPIO-compatible active-low logic. Stack onto your Pi's 40-pin header, connect 24V signals to screw terminals, and read inputs in Python.
Zero power draw from Raspberry Pi. All switching energy sourced from input signals.
Passive design — No onboard regulator or MCU. Requires Raspberry Pi (not included).
Key Specifications
| Parameter | Value |
|---|---|
| Input Channels | 6 |
| Nominal Input Voltage | 24VDC |
| Operating Input Range | 5–28VDC |
| Absolute Maximum Input | 32VDC |
| Output Logic | Active-low (LOW = 24V present) |
| Current per Active Channel | ~2mA (from 24V supply) |
| Current from Raspberry Pi | 0mA |
| Max Signal Frequency | ~1kHz |
Host Compatibility
| Platform | Status |
|---|---|
| Raspberry Pi 4 Model B | Primary target |
| Raspberry Pi 5 | Compatible |
| Raspberry Pi 3 Model B/B+ | Compatible |
| Raspberry Pi Zero 2 W | Compatible (with header) |
| Raspberry Pi 400 | Compatible (via GPIO breakout) |
| ASUS Tinker Board, NVIDIA Jetson Nano, Orange Pi | Compatible (verify GPIO pinout) |
Environmental
| Parameter | Value |
|---|---|
| Operating Temperature | −25°C to +70°C |
| Storage Temperature | −55°C to +150°C |
| Humidity | 5–95% RH (non-condensing) |
Mechanical
| Parameter | Value |
|---|---|
| Dimensions | 65 × 56 mm (2.56 × 2.20 in) — RPi HAT footprint |
| Input Connectors | 6× 5.08mm pitch screw terminals |
| GPIO Header | 2×20 pin female socket (2.54mm pitch) |
| PCB | Lead-free HASL finish |
| Mounting | Direct stack onto Raspberry Pi GPIO header |
Features
- 6 Independent Input Channels — Accept 24VDC from PLCs, proximity sensors, limit switches, pushbuttons
- Zero Power Draw from Pi — All gate drive energy from 24V input, Pi runs cooler
- Industrial Screw Terminals — 5.08mm pitch, 500V rated, accepts 24–12 AWG
- Automotive-Grade MOSFETs — IRLR3410TRPBF, JEDEC JESD47F Industrial-qualified
- Direct GPIO Passthrough — Only 6 GPIO pins used, I²C/SPI/UART pass through unaffected
- Active-Low Logic — 24V present = GPIO reads LOW, 24V absent = GPIO reads HIGH
GPIO Channel Map
| Terminal | GPIO | RPi Header Pin |
|---|---|---|
| H3 | GPIO22 | Pin 15 |
| H2 | GPIO27 | Pin 13 |
| H1 | GPIO17 | Pin 11 |
| H6 | GPIO26 | Pin 37 |
| H5 | GPIO6 | Pin 31 |
| H4 | GPIO5 | Pin 29 |
Typical Applications
- PLC output monitoring with Raspberry Pi data loggers
- Industrial sensor integration for IoT systems
- Machine status monitoring
- Limit switch and proximity sensor interfaces
- Automation system prototyping
Compatible PLCs
Tested with AutomationDirect Click CO-00DD2-D. Compatible with Click PLUS, BRX series, Siemens S7-1200 DC/DC/DC, Allen-Bradley Micro850/870, Schneider M221/M241, Mitsubishi FX5U, Omron CP1L/CJ, IDEC MicroSmart FC6A, and WAGO 750 series. Requires 24VDC sourcing (PNP) transistor outputs. Avoid relay output modules — minimum wetting current may cause unreliable readings.
Regulatory & Compliance
| Requirement | Status |
|---|---|
| RoHS 3 | Compliant — Directive 2011/65/EU + Delegated Directive (EU) 2015/863 |
| Component Selection | All components specified as RoHS-compliant |
| PCB Finish | Lead-free HASL |
| Solder Paste | SAC305 (Sn96.5%, Ag3.0%, Cu0.5%) |
| Third-Party Testing | Not performed — compliance based on component specifications and manufacturing process |
| MOSFET Qualification | JEDEC JESD47F Industrial |
Package Contents
- 1× GS-500 24V Input to RPi GPIO Shield (V1.2)
- Product documentation (PDF download)
Note: Raspberry Pi not included.
Installation & Safety
Intended Use: The GS-500 is a subassembly intended for integration into larger systems by qualified electrical and automation professionals. This product is not a consumer device. Requires Raspberry Pi or compatible SBC (not included).
Installation Environment: The Raspberry Pi and GS-500 assembly must be installed in a properly rated enclosure (NEMA/IP) with appropriate strain relief and cable management. Enclosure not included.
Hot-Swap Warning: Power off Raspberry Pi before connecting or disconnecting the GS-500 shield. Never hot-swap. GPIO damage may result from improper insertion or removal.
Software Configuration: Enable internal pull-up resistors on GPIO pins in your code. Without pull-ups, pins float when 24V is absent, causing unreliable readings. See product documentation for example code.
Ground Reference: When using separate 24V and 5V power supplies, bond the 0V rails at a single star-ground point. Common ground reference is mandatory for proper operation and to prevent damage.
Debounce Requirement: Add software debounce (10–50ms) when reading mechanical switches, pushbuttons, or relay contacts.
Exclusions: The GS-500 is not designed, tested, or certified for safety-critical applications, life-support systems, applications requiring SIL-rated components, explosive or hazardous atmospheres, or direct outdoor installation without appropriate enclosure. Not suitable for high-speed signal acquisition above 1kHz.
Warranty: Warranted against defects in materials and workmanship for thirty (30) days from date of shipment. Warranty does not cover damage from misuse, improper installation, hot-swap damage, operation outside specified limits, or integration failures.
Limitation of Liability: Gestahl's liability is limited to repair or replacement of defective products. In no event shall Gestahl be liable for incidental, consequential, or special damages arising from product use.
Specifications Subject to Change: Specifications and features are subject to change without notice. Consult current documentation at gestahl.com for latest information.
Part Number: GS-500
Current Version: V1.2
Revision History
| Version | Changes |
|---|---|
| V1.0 | Initial Release |
| V1.1 | Increased MOSFET VDS Limit |
| V1.2 | Improved Header Silkscreens For Clarity |