Description
A compact industrial Raspberry Pi, with dual SD card
Strato Pi CM Duo is an extremely powerful and compact industrial server based on Raspberry Pi Compute Module, suitable for use in industrial and professional applications where reliability and service continuity are key requirements.
It is compliant with the low voltage and EMC CE directives, as well as the harmonised standards for electromagnetic compatibility, electrical safety, emission and the RoHS directive for hazardous substances. It is also compliant with the applicable FCC rules and IC standards.
Features
Mounting:
- 2 modules DIN rail case
- power supply and serial connections on pluggable terminal block
Power supply:
- 9-28Vdc power supply, with surge and reverse polarity protection, and 1.1A resettable fuse
- up to 1.9A max continuous current (3A peaks) to the 5V Raspberry Pi Compute Module power supply input pins (at 24Vdc)
Connectivity:
- standard RS-485 interface to the Raspberry Pi serial line, with opto-isolator and electrostatic discharge protection
- 2 x USB 2.0 type-A ports, with individual power control and fault detection
- 10/100 Ethernet port
High reliability and security:
- switchable dual microSD card architecture
- hardware watchdog, fully independent from the Raspberry Pi Compute Module, controlled via GPIO, with dual SD card switch control
- real time clock (RTC) with replaceable back-up battery
- embedded Microchip ATECC608A secure element chip
- integrated boot loader for the Strato Pi micro-controller, allowing in-field firmware upgrades directly from the Raspberry Pi
More:
- GPIO-controlled LED
- LEDs for power supply and serial line activity
- recessed push-button, hidden behind the front-panel, connected to a GPIO pin
Highlights
Fundamental requirements for high-reliability systems, which must guarantee a functional life cycle of many years, are data integrity and redundancy and often the ability of performing a full-system upgrade while operating in remote locations.
The Raspberry Pi Compute Module Lite has two buses for connecting a primary SD card (where the system boots from) and a secondary one.
Strato Pi CM routes its two microSD card holders to these buses through a high-speed switching matrix, controlled by an independent micro-controller. This enables for separate OS/data storage, system redundancy and in-field full-system upgrades.
The SD card to boot from can be configured for a switch upon scheduled power-cycle or upon a configurable number of subsequent watchdog timeout resets.
Strato Pi CM Duo can also be used with the Compute Modules with embedded eMMC flash storage. On these boards only the secondary bus is available and can be routed to the two SD cards, even at runtime, for storage failover or to add additional space.
A hardware watchdog is an electronic circuit that can reset the processor if, for any reason, the software application appears to be stuck. An automatic hardware restart after a software hang can save your day, particularly on unattended applications that need to work continuously.
Taking advantage of the Strato Pi CM on-board micro-controller, we have implemented a hardware watchdog circuit that can be used, upon a software hang, to reset the Raspberry Pi CM.
On Strato Pi CM Duo, the watchdog can also be configured to automatically switch the SD card used for booting the system when the reset is triggered.
The Strato Pi watchdog is completely independent from the Raspberry Pi’s internal CPU watchdog circuit and, being controlled by Raspberry Pi’s GPIO pins, it is extremely easy to control from your application and very effective in recovering from unexpected malfunction.
Strato Pi CM Duo has two USB ports power-controlled by the MIC2076, a MOSFET switch optimized for power distribution with circuit protection. The MIC2076 is internally current limited and has thermal shutdown that protects the device and load. A fault status output flag is asserted during overcurrent and thermal shutdown conditions.
The power-enable inputs and the fault status outputs are routed to the Raspberry Pi’s GPIO to easily control and monitor the connected devices from your application.
Specifications
| Power supply | 9-28V⎓ (VDC)
Reverse polarity protection with 1.1A resettable fuse |
| Current consumption at VS+ 12V⎓
including Raspberry Pi CM 3+ Lite, with Ethernet and RS-485 connected, no USB devices |
low CPU load: 170mA
100% CPU load: 410mA Actual current consumption may vary based on working conditions |
| Current consumption at VS+ 24V⎓
including Raspberry Pi CM 3+ Lite, with Ethernet and RS-485 connected, no USB devices |
low CPU load: 100mA
100% CPU load: 220mA Actual current consumption may vary based on working conditions |
| Raspberry platform compatibility | Raspberry Pi Compute Module 1
Raspberry Pi Compute Module 3 Raspberry Pi Compute Module 3 Lite Raspberry Pi Compute Module 3+ 8GB Raspberry Pi Compute Module 3+ 16GB Raspberry Pi Compute Module 3+ 32GB Raspberry Pi Compute Module 3+ Lite (tested with Pi Compute Module 3 for regulatory compliance) |
| Serial communication port | RS-485 Half-Duplex with automatic data direction management |
| Serial port baud rates | 1200 to 115200 |
| ESD-Protection Voltage on RS-485 A/B | ±15kV human body model
±8kV contact discharge |
| Surge protection on RS-485 A/B | Surge protection up to ±500V/2ohms 1.2/50μs; 600W peak pulse power capability at 10/1000μs waveform |
| Fail safe feature on RS-485 | Yes |
| Real time clock | Internal RTCC circuit with backup lithium battery. Only use CR1220 or BR1220 batteries.
Expected battery life without main power supply: ~2 years |
| Housing | standard 2M for DIN rail |
| Electromagnetic immunity compliance | EN 61000-4-2 (ESD)
EN 61000-4-3 (Radiated RF Field) EN 61000-4-4 (Burst/fast transient) EN 61000-4-5 (Surge) EN 61000-4-6 (Conducted) EN 61000-4-8 (Power frequency magnetic field) |
| Operating temperature | CM1, CM3: 0…+50 °C
CM3+: 0…+60 °C |
| Storage temperature | -20…+70 °C |
| Protection degree | IP20 |
| Weight | 160 g (including Raspberry Pi Compute Module 3+) |