Multiplex Jet Interface
Speed & Tank
Sensor module
Thanks for purchasing the M-Link speed and tank sensor
The package includes :
1 Interface Board
1 cable interface-> M-LINK receiver
This folder.
Optional :
1 Flow sensorcable interface –> Flowsensor
1 EagleTree Microsensor
Required extra : Multiplex USB receiver interface cable #55149,
or old model RS232 receiver cable #85150
Only a subset of M-Link receivers are capable of transmitting telemetry
At the time of writing, the following models will work with the module
#55811 Reciever RX-7-DR M-LINK 2,4 GHz
#55812 Reciever RX-9-DR M-LINK 2,4 GHz
#55813 Reciever RX-9-DR pro M-LINK 2,4 GHz
#55814 Reciever RX-12-DR pro M-LINK 2,4 GHz
#55815 Reciever RX-16-DR pro M-LINK 2,4 GHz
Refeer to Multiplex receiver manual, on where to connect sensors.
Introduction
Measuring fuel level.
Since the fueltank in model airplanes are almost never level, it is quite hard to measure the fuel level in the tank in flight.
This module can monitor the fuel consumption bykeeping track of the amount of fuel used.
It works by utilising a flowsensor in the fuel line between the tank and the engine.
The module assumes that the tank is 100% full when the rx is turned on. From that point the sensor will measure every ml passing, and calculating the remaining fuel in the tank.The module can display remaining fuel in ml, percent remaining, and a ml/min flow, with optional alarm on percent remaining.
Measuring speed.
Measuring speed with GPS is quite possible, but it does not take the wind into account.
If the plane is flying 40 kmh in a 10 kmh headwing, the GPS will only report 30 kmh.
Alternatively the GPS will report 50 kmh when flying 40 kmh, with a 10 kmh tailwind.
By using a speedsensor with pitot tube, this will be overcome, since the pitot tube measures the speed thru the air, regardless of wind.
The module emulates a variometer, so it is possible to hear speed changes by the change in tone from the transmitter, so there is no need to watch the display while flying
When flying too fast the TX will emit two tones with the same pitch, as the speed increases the tones will sound more often.
When flying too slow the TX will emit two tones with different pitch, when the speed drops the tones will sound more often.
When flying the exact speed the module has been programmed for, the TX is silent.
The variometer sound is set with reference speed, by plugging a cable from a vacant channel on the receiver to the module on the “SRV” connector.Assign a switch or pushbutton to the channel.
When the plane is flying the desired speed push the button, and hold for 2-4 seconds.This is the reference speed (Vref).
The module will remember the actual speed at the moment the button was pushed, even when turned off.
If desired the variometer sounds can be reversed to sound different, since the tones normally used for ‘too high speed’ is quite distinct, and similar to a alarm sound.
If using the variometer sound, it is not advisable to use the module together with multiplex variometer #85416, since both modules will make the transmitter emit variometersounds.
The variometersound can be disabled by not assigning a slot to the audio sensor. (see configuring module)
Installation
In order to install it correctly, please follow the instructions.
Place the module in a secure location, a sticky foam pad should be adequate, if necessary reinforce with a cable tie.
Connect the supplied three-wire cable from the RX connector on the module, to the sensor connector on the receiver.
If speed sensor is supplied in the kit, Connect the two-wire cable from the SRV connector to a vacant channel on the receiver.
The cable is only included, when speed sensor is included in the kit.
If using a speed sensor purchased from another source, you must make your own cable.
Use regular servo cable and connectors, but do not connect the + lead.
If the + lead is connected in the SRV-cable, the module may be damaged if the receiver is used with batteries over 5,5 volt.
Configuring M-Link Receiver
Newer receiver software versions has the option to assign one telemetry slot as ‘very important’ and can transmit information for this slot more often than all others.Set ‘vip slot’ to be the same as the variometersound slot in the module, so the speed sound gets updated more often.
Note : the module can be supplied with extra connector to daisy chain additional M-Link sensors
This connector is located between the RX and Speed connectors.
Optionally you can solder your own connector to the pads on the PCB.
If flowsensor is supplied in kit:
Connect sensor cable to the sensor, and the servo connector to the connector in the upper left corner
Compare with drawing on the front of the manual
Install flow sensor between tank and pump.
The manufacture does not recommend to put the flow sensor in installations with pressure above 4 bar
Here installed in a turbine powered model, there is usually no need for isolation from vibrations
The recommended orientation of the flow sensor is vertical, with the label up.
Pay attention to the direction of the flow, follow the arrow on the label.
If sensor is reversed significant inaccuracy will be experienced.
Note
If fuel pump is used, the pump may provide enough suction to cause steambubbles in the flowsensor
If this is the case, move sensor to high pressure side of pump, beware of pressure limitations.
This usually is not a issue with a piston engine, without electrical fuel pump on-board.
Remember to enable flowsensor in the config .
If you purchase your own Flowsensor
If using a flow sensor from another supplier, you must use a flowsensor that can withstand Petrol,/Gasoline, Methanol or Jet A1, and at the same time be accurate
The flowsensor must also be able to work on 5V
The flowsensor must be able to send pulses between 1 and 200 pr. mL
The flowsensor must be able to deliver the maximum flow required by the engine, without introducing too much flow restriction.
If speed sensor is supplied in kit :
Connect speed sensor to board, compare with the drawing on the front of the manual
Remember to enable speed sensor in config
Determine the speed range for which you intend to set the reference speed
(for a glider tug, this will be quite higher than a approach help for a jet)
Notice the AOA of the model at this speed
For best function, the pitot tube should be aligned with local airflow at the AOA of the most used reference speed.
Anything better than +/- 5 degrees is adequate,
however the accuracy of the pitot tube will increase with accurate alignment.
The pitot tube must be placed OUTSIDE the propwash,
otherwise the pitot tube will sense the propwash speed, instead of model speed.
3.rd party purchased speed sensor.
If at a later date a eagle tree speed sensor is purchased from another vendor, it may not be configured to be used with this speed&tank sensor.
To properly configure the eagle tree micro speedsensor to be used with this module, you will need the eagle tree V3 datalogger, associated USB cable, and configuration software
Connect the speed sensor to the datalogger, start the windows software, and connect the USB cable to the datalogger.
Please refeer to the eagle tree manual for datalogger on how to connect to the datalogger, and start eagletree software.
Change the speed sensor to 3’rd party protocol : On the eagle tree screen -> advanced -> 3’rd party 
Save configuration, and disconnect speed sensor
The speedsensor is now configured for use with M-Link Speed&Tank module
Module Configuration
To configure the device, the Multiplex cable #55149, or #85150 is required, in addition to the configuration software, found here
If using #55149:
Download and install the usb driver from multiplex homepage
There is no need to install the configuration software, just download and unpack
After plugging in the USB interface, check with device manager, what com-port is assigned to the USB interface.
The device manager can be found by right-clicking on ‘my computer’, and select ‘properties’
Select the tab named ‘hardware’
Select Device manager
Find the com port number in the device manager
This is the software interface of the present version V. 1.5
This software works with all models and present versions of hobbytronic sensors
When starting software, this is the opening picture
1 – Connect MPX cable to module installed in plane
2 – Press “open” to enable the software to discover the module
3 – turn on receiver
The program will now poll the module for the current configuration, and display it
To change the values, use the dropdown boxes to select the telemetry slot in the TX where the telemetry value is going.
Telemetry slot :
This indicates which slot on the TX where the value will be shown:
This shows ref speed in slot 3, present speed in slot 4, and ‘variometer’ in slot 5.
Secondary values:
The secondary value to speed is alarm for overspeed (Vne)
The secondary value to Tank Vol % is the alarm value for low tank.
The secondary value for Audio is the scaling factor for the ‘variometer’ sound, a good starting value is ‘10’, in the picture above the scaling factor is 5
Fuel Values
Tank Vol. mL. : enter the fuel capacity in mL, this is used to calculate remaining fuel.
Fuel click/ml : this value is the number of revolutions of the flowsensor for each mL of fuel passing.
For the supplied (if supplied) flowsensor this value is around 10 pulses per mL
In some installations where there is a lot of vibrations, the flowsensor will measure too much fuel passing,
The impeller inside is vibrating, too much.Lower the sensitivity by increasing this number,
Calibrating flowsensor
If the amount shown in the display are too high, compared to the actual amount in the tank, increase click/mL
If the amount shown in the display are too low, compared to the actual amount in the tank decrease click/mL
When finished changing the configuration, press “store” and “close”
Turn of the receiver, and disconnect cable.
The module is now ready for use, and will remember the setting at next turn on.