STEVAL-SILPLC01 [STMicroelectronics]

The STEVAL-SILPC01 is a PLC solution with a 1oo2 architecture, featuring the CLT03-2Q3dual channel digital input and the IPS160HF single channel digital output.

The hardware is designed to meet the SIL level. It has been officially assessed by TÜV Italia (TÜV SUD Group) in compliance with SIL 2 / PL d requirements: random failure rates, systematic capability (for the hardware), architectural constraints in accordance with IEC 61508, EN 62061, EN ISO 13849-1, and EN ISO 13849-2 standards.

The system is built around the STM32H723VG microcontroller. It is able to manage connectivity, load actuation and system diagnostic check for power management, digital input/output ICs, and temperature monitoring at the same time.

The solution integrates DC-DC converters in a buck configuration powered by the L7987L and L7983. The switching converters have been designed to provide 3.5 V on the user side and 6 V on the isolated side. With dedicated post regulation circuits, these voltage levels are stepped down to 3.3 V for the MCU, connectivity, and temperature sensor (available on the isolated side) and 5 V for the signal delta isolator (also available on the isolated side).

The CLT03-2Q3 input can detect a fixed DC voltage via a 0-36 V or 4-20 mA sensor, whereas the two IPS160HF allow load driving with a 2.5 A current capability for each output.

Several diagnostic and protection circuits are available on the board to ensure the system proper functionality and meet the IEC61508-2 requirements.

The hardware is supported by STSW-SILPLC firmware package, based on the STM32Cube architecture. It consists of an application layer, a drivers layer with BSP/CMSIS and HAL library, and a middleware layer.

The firmware solution embeds the EtherCAT protocol stack V5.0.8 and X-CUBE-STL-H7 v1.2.0 certified by TÜV Rheinland. The stack library provides dedicated APIs to handle the data packet exchange between the master and the slave. Data consist of a set of commands to drive the load through the on-board IPS on board and manage system diagnostic using dedicated signals. These data types are exchanged using the process data channel of the protocol stack.

A daisy-chain configuration can be implemented to connect more than one sensor node to the same network. In this case, the master generates a common frame with the data to be addressed to all EtherCAT slaves (ECS). Each node identifies its own frame by verifying only the MAC address reported in the frame.

Dedicated documentation related to TÜV assessment on the hardware, such as TN1395 Analysis of hardware systematic failures and techniques for on-chip redundancy, FMEDA, Assessment on hardware Report TI 722260614 Rev. 0, and the industrialization package, as well as the user manual, are available on demand, by signing a specific NDA.

• Built around the following ICs for the industrial market:
  • STM32H723VG: Arm® Cortex®-M7 32-bit RISC core operating at up to 550 MHz
  • CLT03-2Q3: self-powered digital input current limiter
  • IPS160HF: Single channel high-side switch
  • L7987L: 61 V 2 A asynchronous step-down switching regulator
  • ISOSD61: 16-bit isolated sigma-delta modulator, single-ended and LVDS interfaces
• Main supply voltage: 24÷36 V (max 60 V)
• Power management circuit for digital circuits voltage reference generation
• Designed to meet IEC61508 SIL 2 level
• Hardware assessed by TÜV Italia (TÜV SUD Group)
• Inductive load demagnetization and direct output diagnostics available on board
• X-CUBE-STL self test library certified by TÜV Rheinland
• Real-time communication with EtherCAT
• RS485 PHY
• Six-layer stack-up to improve immunity on real-time communication
• RoHS