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SAE J2716 (SENT) Protocol

There is a data communication protocal SAE J2716 "SENT" (Single Edge Nibble Transmission).  It's used for inexpensive automotive sensors in high noise environments.  The SENT protocol transmits as a series of pulses with data measured as falling edge to falling edge times. http://www.designnews.com/article/CA608455.html



My problem is that I need to simultaneously sample three types of data including SENT:
1. Analog channels (easy).
2. Quadrature from an encoder (easy with the right DAQ device).
3. S.E.N.T. data (hard).

Is there a way to configure the a DAQ device to do this counter/timer logic right on the card? A couple years ago, quadrature was added as a possible data channel for certain DAQ devices.  I was wondering if SENT could also be available using the correct configuration and the right hardware. I know that an FPGA could do this, but that is a lot more work than I can invest.  Any suggestions?
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Message 1 of 26
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Hi dualtronic,
 
We currently do not have an out of the box DAQ device that can be configured on board to do SENT. It may be possible to implement the protocol in software using DAQmx but in that case it would probably make more sense to use one of our FPGA devices (for more control of timing and behavior).
 
 
Regards,
Adam
 
Applications Engineering
National Instruments
Adam

National Instruments
Applications Engineer
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Message 2 of 26
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Hello Adam,

 

Do you (NI) already provide example code for LabView and an R device to decode and transmit SENT ?

 

for the 7831 R and LabView 8.6 for example...

 

Best Regards

Maxime 

 

 

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Message 3 of 26
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I have developed a small circuit board that is 2.25" square that directly converts a

SENT signal into two 16-bit analog output voltages.  I could probably sell you one

(or some) of these boards.  Visit my site http://www.biltronix.com, enter the

Biltronix site and send me an email from there and mention this thread.  There is no

information on my site about the board because I developed it very recently.

 

I use this new board to convert the SENT output of DC-motor powered throttle bodies

with Hella position sensors into analog signals.  This allows the valves to be tested

and cycled on existing equipment that was built for products with analog inputs.  The

analog signals are easy to capture with Labview or any other common data logger.  I

also have developed a very nice small closed-loop controller board/box that operates

the DC-motor type valve assembly.  This board/box is used as a single-channel desktop

controller and has been used underhood.  The closed-loop controller boards have also

been installed in groups inside larger boxes to cycle multiple parts.  The controller

has a dial that you can turn to control the position of the valve.  It also accepts

PWM and analog reference signals and it has a PWM status output.  My point here is

that the closed-loop controller was built to accept 1 or 2 analog position sensor

inputs, not SENT, but by hooking up the SENT-to-analog converter board, there's no

more problem.

 

My SENT converter board runs on +6V to 20V and it has reverse polarity protection and

transient protection.  It powers the SENT sensor with a regulated +5V output.  It

syncs to and reads and analyzes the entire SENT pulse frame.  It checks for valid

sync and nibble pulse times, normalizes the nibble pulse times to the sync time, then

converts the nibbles to data.  Then it checks the checksum and applies some other

error detection tests as well.  If all is well, the data is converted into 12-bit

word values and then loaded into a pair of 16-bit precision DAC's.  The voltage

outputs are then buffered and available at a set of plug-in screw-terminal blocks

where you can easily attach wires.

 

The board has a two-color LED on it that indicates the operating status.  If it is

green, everything is running perfectly.  If it is red, there is some sort of error

converting the SENT signal (ie: bad checksum, sensor is indicating a fault, data is

incorrect, etc.).

 

The board also has a serial interface that can be connected to a PC using

HyperTerminal or other terminal application.  Using the interface, it is easy to runs

tests on the board (it tests itself thoroughly) and to manually control the two

voltage outputs.  There is also an output scaling feature so that you can change the

output range if desired.  At present, the board converts every SENT frame in real

time with scaling off but most people prefer that mode anyway.  With scaling turned

on, it converts every other frame.  I am thinking about adding a "bootloader" feature

so that the end-user can update the firmware from their PC.  It is likely that I will

be producing new firmware in the future that will handle different SENT-type sensors.

 I presently have firmware only for the position sensor type such as that presently

used on GM ETC.

 

The board also has a few test points including ground, wave-shaped buffered digital

SENT output, +5V output, +2.5V reference output.

 

In case anyone is wondering, my SENT-to-analog converter board is based on a 40 MHz

PIC microcontroller that is programmed (flashed) on-board through a dedicated

programming interface or (if supported by firmware bootloader) through the serial

port interface.  I designed and built the entire board myself and wrote all of the

source code as well.

 

To anyone who is interested in this converter or if you'd like me to do some custom

programming for your application, please just go to my site and email me from there. 

I won't likely be checking back to this forum.

 

Cheers

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Message 4 of 26
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Hello,

 

Thank for your response ! but that's not whatr I'm looking for.

 

I'm intersted in Labview or LabWindows Solutions based on R-Series Hardware (7831 for example). Voltage driver or other electronic will be done on myself.

 

sincerly,

 

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Message 5 of 26
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Good Afternoon MaximeMT,

 

We have example FPGA code at www.ni.com/ipnet; there is not currently an example for SENT.  However, you may be able to base your code on one of the communication protocols which is posted.

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Message 6 of 26
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I am looking to write  some code for the SENT Protocol and found this thread and wanted to ping it and see if anyone has writtent any LabVIEW code for the SENT protocol in the last few months.

 

Regards

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Message 7 of 26
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Just checking to see if anyone has written any SENT protocol labview code
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Message 8 of 26
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Hello!

 

Did you find any SENT protocol labview code? Do you have any?

This could help me...

 

Thanks!,

Crisansa

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Message 9 of 26
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I have developed a SENT reader using labview, implementable on CompactRIO. It essentially requires a digital I/O Card and FPGA. If anyone needs it, drop me a message

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Message 10 of 26
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