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How do I add water and diesel sensor?
(2017-03-04, 04:27 PM)PaddyB Wrote:
(2017-03-02, 01:54 PM)affinite Wrote: OK answered my own question ...
A bit of experimenting and I have my MCP3208 working in SPI/OP and can see the output in the SignalK diagnostic window.
Now to get my head around SignalK/NodeRed to display the result Smile

If you haven't figured it out already this might help a little, its part of a node red flow I use to display engine temperatures. It uses to dashboard nodes to display -
I put a delay node in as well otherwise there was too much data for the graph. 

Hope this might be of use. 

PS Ctrl-i opens the nodes import dialog box.

[{"id":"12d9eb57.4dee05","type":"websocket in","z":"a1ba0b6c.b93d98","name":"SignalK input","server":"58d1334a.a72ecc","client":"","x":75,"y":98,"wires":[["11b86291.f8905d"]]},{"id":"11b86291.f8905d","type":"json","z":"a1ba0b6c.b93d98","name":"","x":96,"y":208,"wires":[["7517c8ee.de2b48","dbc2f1fc.c6e78","bc5087ef.c78118"]]},{"id":"7517c8ee.de2b48","type":"jsonpath","z":"a1ba0b6c.b93d98","expression":"$.updates..values[?(@.path==\"propulsion.Eng.temperature\")]..value","split":true,"name":"EngTemp","x":264,"y":100,"wires":[["29d547b8.f04588"]]},{"id":"29d547b8.f04588","type":"delay","z":"a1ba0b6c.b93d98","name":"","pauseType":"rate","timeout":"5","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"minute","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":true,"x":408,"y":52,"wires":[["7e631a32.8bc014"]]},{"id":"7e631a32.8bc014","type":"function","z":"a1ba0b6c.b93d98","name":"Convert to deg C","func":"var numInput = Number(msg.payload);\nmsg.topic = \"Eng\";\nvar T =  numInput-273.15;\nmsg.payload = T.toFixed(0);\nreturn msg;","outputs":1,"noerr":0,"x":592,"y":88,"wires":[["66a37c6d.494d34","d864e825.200108"]]},{"id":"d864e825.200108","type":"ui_chart","z":"a1ba0b6c.b93d98","name":"EngineGraph","group":"67dca234.faad9c","order":0,"width":"23","height":"7","label":"Engine temperature history","chartType":"line","legend":"false","xformat":"%H:%M:%S","interpolate":"linear","nodata":"","ymin":"","ymax":"","removeOlder":"4","removeOlderUnit":"3600","x":829,"y":73,"wires":[[],[]]},{"id":"66a37c6d.494d34","type":"ui_gauge","z":"a1ba0b6c.b93d98","name":"EngTempGauge","group":"8861c889.240108","order":1,"width":"3","height":"3","gtype":"gage","title":"Engine temperature","label":"Deg C","format":"{{value}}","min":0,"max":"120","colors":["#00b500","#e6e600","#ca3838"],"x":911,"y":203,"wires":[]},{"id":"58d1334a.a72ecc","type":"websocket-listener","z":"","path":"ws://localhost:3000/signalk/v1/stream","wholemsg":"false"},{"id":"67dca234.faad9c","type":"ui_group","z":"","name":"Engine/Alt/Exhaust temporature history","tab":"1d99b92f.cedb87","disp":true,"width":"23"},{"id":"8861c889.240108","type":"ui_group","z":"","name":"Temperature gauges","tab":"aeffa403.23f5f8","disp":true,"width":"19"},{"id":"1d99b92f.cedb87","type":"ui_tab","z":"","name":"Graphs","icon":"dashboard","order":2},{"id":"aeffa403.23f5f8","type":"ui_tab","z":"","name":"Gauges","icon":"dashboard","order":1}]

Look Sunday is now OP/NodeRed day !!
Thanks in part to PaddyB I now have my tank levels in NodeRed displaying wonderfully.
I do have a problem accurately measuring the input voltage to the MCP3008 ADC and wondered how others had dealt with this.

I am using a simple voltage divider with my 0-190 ohm resistive tank senders to send a measured voltage representing the tank level to the ADC. The problem is that this is susceptible to variations in the supply voltage which can cause inaccurate readings on the ADC.
The second problem is that at a supply voltage of 5v with a (lowest) resistance of 100 ohms each voltage divider is drawing around 50ma. I have 4 tank senders so Im drawing 200mA just for the senders.

Does anyone know a better way of sending the tank levels in a way that is more accurate and draws less current ? I assume Im talking about OpAmp circuits but I'm not capable of designing my own circuits so any help appreciated

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Affinate, what sensors are you using? Do you have a spec on them.
(2017-03-16, 05:21 PM)henker Wrote: Affinate, what sensors are you using? Do you have a spec on them.

Im using DS18B20 1 wire sensors (as specified for OpenPlotter) for temperature
For fuel I'm using a 190ohm resistive float sender by Wema. This was the original fuel sender. 
For water etc I plan to use further WEMA senders like this one wema sender
What about the following; This is what I'm planning to use for my water tank.:
(2017-03-26, 08:29 PM)henker Wrote: What about the following; This is what I'm planning to use for my water tank.:

Looks good. 
Low current consumption 1.2mA !
I'd be interested to hear how you get on with it.

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