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EFIS spec

A

Aviator168

Well Known Member
Anyone here have a link to the EFIS bus and protocol spec? Making some data acq and display units. Thnx.
 
Aviator168 said:
Anyone here have a link to the EFIS bus and protocol spec? Making some data acq and display units. Thnx.
Click to expand...
The closet thing to a universal standard is ARINC 429, but it costs money to purchase the standard. However, many of the experimental EFISs use their own proprietary busses and communication specs. If you want to make a box that can talk to all the popular EFISs, you'll need to support multiple busses and comm protocols. You may also need to reverse engineer some of the proprietary busses and communication specs, as some manufacturers don't want to make this data available. If they start losing sales because their EFIS can't connect to popular devices, maybe they will change their mind and fully support public standards and/or publish the specs for their proprietary busses and communication protocols.
 
ARINC 429 is what I could find on the net. However, I thought the spec was free. Guess not.

After all this years, you would've thought that they (manufacturers) all have come to an agreement, haven't they. Well, guess I have to make up my own protocol. However, I am going to release it to the public domain and whoever want to fab his own equipment/display can do it themselves.
 
Aviator168 said:
ARINC 429 is what I could find on the net. However, I thought the spec was free. Guess not.

After all this years, you would've thought that they (manufacturers) all have come to an agreement, haven't they. Well, guess I have to make up my own protocol. However, I am going to release it to the public domain and whoever want to fab his own equipment/display can do it themselves.
Click to expand...
There seems to be quite a bit of ARINC 429 info available on-line. There might be enough info to make a device that can receive and transmit ARINC 429 data. I think you'll have a lot more success if you make a device that uses an already available, somewhat popular protocol than if you invent yet another protocol and expect other vendors to update their device to talk to yours.

The CANaerospace/AGATE databus might be worth looking into. I don't know if it is going to become popular or not.
 
CanAerospace

Checkout CANaerospace. There is also an AINC id but I forget what it is.
 
Thnx. I rather adopt a standard format. I found an ARINC to RS232 bridge device. It's very small and draws power from the RS232 from the PC. There are two receive channels and two transmit channels. Once I get the data to the PC, I can do whatever I want with it. I have a few applications mind that I haven't seen in the market.
 
One thing about the hardware interface of ARINC that I am still not that clear is that from messages on the board it seems to me that the number of devices can receive information is limited by the number of ports in the transmitting device. However, from documents on CANaerospace's site, it gave me the impression of that the ARINC bus is one single unit (like coaxial ethernet) where every device can talk to every other device. Am I right about this?
 
Aviator168 said:
One thing about the hardware interface of ARINC that I am still not that clear is that from messages on the board it seems to me that the number of devices can receive information is limited by the number of ports in the transmitting device. However, from documents on CANaerospace's site, it gave me the impression of that the ARINC bus is one single unit (like coaxial ethernet) where every device can talk to every other device. Am I right about this?
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ARINC is a single transmitter that can be connected to multiple receivers.
This is why most equipment has a limited number of transmitters (usualy 1) and multiple receivers.
This requires more cable but does prevent single point of failure to some extent (not sure if that was intended).

But there is trouble with ARINC. Due to vague documentation implementation between systems can be very different. Some may send certain labels, others don't, yet others send the labels but change some of the contents to suit particular uses. In other words - it's become a bit of a mess.

It's the closest thing we have to a universal standard though - but it sucks.

CAN AeroSpace is one way out - but nobody uses it (even though we have a CAN Aerospace interface on our Voyager and Odyssey - it's for now dormant. Perhaps the future will change this).

Rainier
CEO MGL Avionics
 
Yeah. Kind of like ISDN and SIP. I have been in telecom for many years. Back in the 80, they said ISDN is supposed to make every thing simple. What happened was every manufacturer made up their own twist to gain a little advantage over others. Now, we have different number favors of the protocol which I can't count with my hands. Same thing is happening to SIP, but at least SIP is controlled by the public domain. For a new guy like me going into avionics, it is better to have support for a sub-sub set of ARINC.
 
Hello Rainier,

I just scan through your site. One question. Can your radios/NDB/DME/VOR be controlled externally by a computer? Thnx.
 
jdeas said:
Checkout CANaerospace. There is also an AINC id but I forget what it is.
Click to expand...

The CAN bus is different from ARINC 429. There are many CAN bus interface products out there and they are very inexpensive. Not the same thing can be said about the ARINC 429 interfaces.
 
Aviator168 said:
Hello Rainier,

I just scan through your site. One question. Can your radios/NDB/DME/VOR be controlled externally by a computer? Thnx.
Click to expand...

One answer: Yes. They are remote units that need to be fully controlled by an EFIS or suitable "passive" panel. As usual we will document the protocol required.

Note that we do not have plans for NBD/DME at this stage. The nav radio we are now busy with does VOR, ILS, Glide slope and has a marker receiver. It can also be used as second VHF COM rx channel.
NDB/DME has largely been replaced by GPS (and a good thing too).

Rainier
CEO MGL Avionics
 
CANaerospace

I gave a paper at Osh based on CANaerospace and it's future. You can check it out at jadsystems.com if your still interested in looking for a standard avionics bus.
 
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