Additional pressure/temperature sensor hook up?

[Karl Buchka]

I understand that there are a few extra analog inputs piped to the EC18 connector. If I wanted to hook up, say, the differential pressure sensor sold in the Webshop, how would I go about displaying and datalogging the input in Megatune?

I'm assuming it's just a matter of connecting the Vout pin of the sensor to one of the pins specified in the User Guide and adding a 'gauge' in the vemsv3.ini file.

What about additional temperature sensors?

It would be fun to datalog at least backpressure in the exhaust collector, and possibly pressure/temperature drop across the intercooler.

Thanks,

Karl

[gunni]

I´m looking to do this soon as well.

Any tips appreciated

[Sprocket]

There are spare ADC inputs, some onboard and not on the EC18. The Fuel Pressure and Exhaust Back Pressure inputs on EC18 are more often used for other inputs, I cant remember which, but the knock channels sounds familiar. These two inputs, FP and EBP are logged as a voltage only, they have no adc hex files to scale the signal, which the likes of the coolant and air temp files have. What you have to do is log the voltage and refference that to your sensor scale manualy.

I looked into this some time ago with a 0-5v pressure transducer. The FP and EBP are a sensor input (5v pull up), rather than a transducer input(volt free), there is some filtering circuitry before it finaly gets to the ADC chip. The onboard channels dont have this filtering and the signal tends to jump around.

Have a look here for some of my babblings

http://www.vems.co.uk/forum/index.php?topic=358.0

[Karl Buchka]

There are spare ADC inputs, some onboard and not on the EC18. The Fuel Pressure and Exhaust Back Pressure inputs on EC18 are more often used for other inputs, I cant remember which, but the knock channels sounds familiar. These two inputs, FP and EBP are logged as a voltage only, they have no adc hex files to scale the signal, which the likes of the coolant and air temp files have. What you have to do is log the voltage and refference that to your sensor scale manualy.

I looked into this some time ago with a 0-5v pressure transducer. The FP and EBP are a sensor input (5v pull up), rather than a transducer input(volt free), there is some filtering circuitry before it finaly gets to the ADC chip. The onboard channels dont have this filtering and the signal tends to jump around.

Have a look here for some of my babblings

http://www.vems.co.uk/forum/index.php?topic=358.0

Sprocket, thanks for the info!

Just to clarify, when you say 5v pull up input, you mean that it's set up for reading a changing resistance, like for the IAT or CLT sensor? In that case the EBP and FP inputs would be ideal for a pre-turbo air temp sensor, and maybe oil temp or ambient temp. The other inputs are then set up without the pull-up, making the suited for transducer inputs, correct? I'll probably be using the same pressure transducer as I did for my MAP sensor, so I guess I could just replicate whatever filtering is already onboard for the MAP circuit if the signal is too 'jumpy'.

[Sprocket]

I would advise looking at the schematic drawings to get an understanding of how these inputs work, it will eventualy make sense. Both the EBP and FP inputs still need a jumper wire installing onboard.

Yes the EBP and FP inputs have a 5v pull up installed on the board and are a resistance device

Normally something termed a sensor is a simple varying resistance device and a transducer is a device that takes one signal type (resistance) and changes it tosomething else (0-5v)

Transducers are normaly externaly powered while sensors are not powered.

Sensors have two wires, one usualy attached to sensor ground and the other to the input, the sensor then pulls the (pull up) voltage low, the voltage then depends on the resistance.

Transducers have three wires, 5v and ground in, and the 0-5v signal out

Dont get confused between a pressure transducer and a pressure sensor, they are two very different things.

http://www.vems.hu/wiki/index.php?page=GenBoard%2FUnderDevelopment%2FAnalogInputs

http://www.vems.hu/wiki/index.php?page=GenBoard%2FUnderDevelopment%2FDigitalInputs

http://www.vems.hu/wiki/index.php?page=GenBoard%2FVerThree%2FSchematic

[Karl Buchka]

Thanks for the links. 

I managed to assemble my VEMS and build the onboard MAP setup from scratch (http://picasaweb.google.com/kbuchka/1979Volvo242#5256891080795741890) so hopefully I should be alright. Just need to sit down and peruse the schematics/wiki when I have some downtime next week. I've got a rolling road session booked for this coming weekend, so I've got some other more important issues to deal with first.