Example program 2: Application of the SENT protocol with EL1262-0050

SAE J2716 SENT (Single Edge Nibble Transmission)

The SENT protocol is a point-to-point scheme for transmitting signal values from a sensor to a controller. It is intended to allow high resolution data transmission with a lower system cost than available serial data solutions. ⁽¹⁾

Hardware

The SENT protocol is a one-way, synchronous voltage interface which requires three wires: a signal line (low state < 0.5V, high state > 4.1V), a supply voltage line (5 V) and a ground line.

Protocol

Data is transmitted in units of 4 bits (1 Nibble). The interval between two falling edges (single edge) of the modulated signal with a constant amplitude voltage identifies the beginning of a frame and must be evaluated on the receiver side.

Fig.210: SENT protocol

A SENT message is 32 bits long (8 Nibbles) and consists of the following components:

• 24 bits of signal data (6 Nibbles) that represents 2 measurement channels of 3 Nibbles each (such as pressure and temperature)
• 4 bits (1 Nibble) for CRC error detection
• 4 bits (1 Nibble) of status/communication information

Implementation of the Control

Fig.211: Extract of the ST implementation within TwinCAT

Example 2: Reading the SENT protocol

Download TwinCAT 2: (Example program)
Download TwinCAT 3: (Example program)

• Hardware requirements:
• EL1262-0050
• EL9505
• A control that allows at least 1 ms task cycle time (IPC/ CX)

The EL1262-0050 is able to work with an oversampling of 1 µs and also 1000 Bit per 1 ms are available.

A Sent telegram has a resolution of 3 µs per digit. So, if 1 µ resolution will be used, it is enough to interpret the received data signal.

Connection diagram:

Fig.212: Wiring for example program 2