DLC (Double Layer Capacitors) for safe shutdown
It should not happen during normal operation on a modern train, but still a power failure is “real life”.
Here the railway standard EN 50155 and its S2 class demanding a bridging of 10 milliseconds are not sufficient at all.
In the past a good luck was necessary not to find a corrupted operating system and/or application program after restarting the control system. Mostly it was an acceptable flaw to miss the last data only. Much more efforts have to be required and serious consequences follow if a fast service is not available:
• Exchange of HMI – if on-hand
• Extra costs for service and new software installation and configuration
• Vehicle out of order
This widespread issue can be avoided with a helpful solution based on an implemented uninterruptible power supply with double layer capacitors.
Our approach – for all our Multifunctional Displays from 8.4” to 15” – provides comfortable 30 seconds for data saving, shutdown of application and operating system.
The lifetime of typically 15 years goes hand in hand with the defined HMI lifetime.
This means: No maintenance interval must be considered.
nvSRAM – ideal combination of short access times and non-volatile storage
The nvSRAM (non-volatile Static Random Access Memory) is a fast and efficient non-volatile memory combining the performance of a fast SRAM with the advantages of a non-volatile cell (EEPROM):
• Internal capacitor guarantees automatic store regardless of power-down slew rate
• Infinite write and read cycles
• Data retention 100 years
The function in brief:
In an nvSRAM each memory cell unites two function elements, namely a SRAM cell and a non-volatile one (EEPROM). In case the nvSRAM device detects a power-down, it stops further activity and automatically initiates a complete store of its content to the non-volatile memory. This process is powered by the energy stored in the internal capacitor. Once the store operation is completed, data retention is specified with 100 years (!) and completely independent on the capacitor voltage. Later, when the HMI returns to normal operation, data are transferred back to the SRAM cell.
Even if the industrial Compact Flash/CFast cards are continuously improved regarding data safety, in case of an unexpected power failure no warranty for data retention can be given.
That is why more and more customers appreciate the additional presence and the benefits of an integrated nvSRAM for parts of their application, such as storage of configuration data, fault reports with timestamps or operating hours. For example, this information can become extremely useful for the investigation of insufficient maintenance and control system failures.
HMI integrated nvSRAM is available with 32 kB for BC3, BC4, BC5 and BC6 Series.
Both options are now ready to order!
