Servers by jDrones

Sending Pixhawk 2.1 TELEM1 data via RJ45 cable


(Zuber) #1

Greetings everyone,

I am currently working on a tethered drone and wanted to make a couple of changes to the data transmission and I need some help regarding it.

Earlier for telemetry data transmission, I used RFD900+ to connect to the mission planner but now I want to eliminate the wireless transmission and in place of that I want to transmit telem data using RJ 45 cable.

So here is what i am in a need to do:

I want to transmit the telemetry down to the laptop using an RJ45 cable in order to connect it to the mission planner.

Since pixhawk telem1 has a signal voltage of 3.3V, can I treat it as an RS232 signal? If yes can I use this converter to fulfil my purpose

[RS232 TTL To Ethernet RJ45 Converter Network Module] (https://www.banggood.in/RS232-TTL-To-Ethernet-RJ45-Converter-Network-Module-p-74491.html?cur_warehouse=CN)

Can anyone help me to get started to find a solution for this?

Any help is appreciated.

Thank you.


(James Pattison) #2

The link didn’t work, but assuming it’s similar to this: https://www.iot-store.com.au/products/serial-uart-ttl-to-ethernet-module-usr-tcp232-t2
Then yes, it will be fine driving it from a Pixhawk uart. Whether or not it’s directly readable via a virtual com port or you’ll need to code something at the other end I have no idea.


(Corrado Steri) #3

Maybe an easier implementation is to use a companion computer with mavproxy to send telemetry trough ethernet.


(Zuber) #4

.
Thank you for helping me out.

Yes, the product in your link is same as mine. @james_pattison

Ok that means I can use this module for my solution, as far as the connectivity to mission planner is concerned I can use rj45 to USB converter to connect to the mission planner avoiding the virtual com port, converting data back to TTL level and connect to mission planner using a com port just like conventional way to connect.

The pin configuration of pixhawk telem port includes:
5v
Rx
Tx
CTS
RTS
GND

The pin configuration of RS232 TTL To Ethernet RJ45 Converter Network Module is
CFG
Rx
Tx
RST
GND
VCC
VDD

So, I am a little confused about connecting telemetry pins to the converter module. Please help me with this one too!

@Corrado_Steri thank you for your suggestion, I know I can do that as well but as the drone will be tethered and has the involvement of cables so, I am going with the ethernet cable for the telemetry connection and I am curious to make this functional.


(ppoirier) #5

Are you tethering power as well?
If not, you just need one twisted pair tx-rx + ground connected to a FTDI serial to USB on the GCS. At 56kbps you should be good for 100 meter


(Zuber) #6

@ppoirier , that’s a good idea too but the thing is that my ethernet cable is twisted with the power cable already so, I just want to utilize the ethernet cable available to me so that I can send my video feed via the ethernet cable as well, eliminating the RFD and video transmitter.


(ppoirier) #7

That would be so simple with my BBBMINI… just connect to thet Ethernet port and send Mavlink & Gstreamer downlink :wink:
Question: what s the total weight of the cable assembly ?


(Zuber) #8

Well, for now, I just want to stick to the Pixhawk cube, maybe I will give it a try next time.

Total weight of my wire is 4Kg.

I have not bought the serial to ethernet converter module yet and before that, I want to confirm the connection to the pixhawk telem1 port.
Will it work if I only hook up connections like this:

Pixhawk telem1 ---------> RS232 TTL to Ethernet Converter
5v -----------------------> VDD
Rx ------------------------> Tx
Tx ------------------------> Rx
CTS -------------------------> –
RTS ------------------------> –
GND -------------------------> GND

Please correct me if I am wrong.


(James Pattison) #9

That’s correct, for hooking it up. Whether it will “just work” we can’t tell you without knowing how the data is presented to the pc.
Patrick’s suggestion takes some guesswork out, so is worth considering.


(Zuber) #10

I will give it a try now and will update my results to you guys. In case if this causes trouble then I will be updating it here.

Thanks for your help. @james_pattison


(mike kelly) #11

Just a reminder that you will need an extra 4kg of thrust to overcome the weight of the cable. It is just like any other “load” on the aircraft.


(Zuber) #12

I have already figured that out and my test flights have been successfull so far. @mike


(mike kelly) #13

Good! …l…