Today's Message Index:
----------------------
1. 07:18 AM - Re: ARINC 429 wiring practices (Christopher Cee Stone)
2. 08:10 AM - Re: ARINC 429 wiring practices (David Josephson)
3. 08:24 AM - Re: ARINC 429 wiring practices (Robert L. Nuckolls, III)
4. 12:57 PM - Re: ARINC 429 wiring practices (Charlie England)
5. 02:36 PM - Re: ARINC 429 wiring practices (Charlie England)
Message 1
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Subject: | Re: ARINC 429 wiring practices |
Hello Charlie,
My -8 panel is holds a 430W, AF4500, ARINC module, AF3500 and AF-pilot.
I followed the AFS wiring schematic exactly. No shielded cables except for
the run to the magnetometer and serial port connections. All remaining
connections between the ARINC 429 module, the 430 and the AF4500 are AWG22
single wire bundled into a harness with zip ties.
I attached the ARINC 429 box to the underside of the AF4500 with self
adhering velcro. Thus all signal wire runs are short, less than 24 inches.
System works flawlessly.
[image: Inline image 2]
[image: Inline image 3]
Chris Stone
RV-8
80802
On Sun, Jul 26, 2015 at 12:11 PM, Charlie England <ceengland7@gmail.com>
wrote:
> I'm in the process of wiring my panel, which includes an old Garmin 430
> (non-WAAS), an AFS AF4500S EFIS, AFS ARINC module, and AFS Pilot
> autopilot. I'm using the AF3000-4000 Installation Guide, v7.4. Looking
> through the AFS docs, their wiring diagrams are a bit...inconsistent... on
> how to treat the ARINC and serial port data wiring.
>
> So I did some digging in the InterWebs to find the 'proper' way to wire
> ARINC 429 stuff. Two different sources say to ground the ARINC 429 shield
> at source, destination, and at every 'break point' where additional
> receivers are added, in daisy chain fashion. Easy enough; I can handle
> that.
>
> There are 3 ARINC data runs between the ARINC module and the 430. Should
> each get its own shielded twisted pair, or would it be kosher to run 3
> pairs in one shielded cable (and/or variations on that theme)?
>
> In various places, there are both single and bi-directional serial runs
> between/among the EFIS, 430, and other devices. In one case, they specify
> that a ground return *isn't needed* (obviously depending on system
> ground(s) between the EFIS & the 430). In most cases, they show a separate
> ground return wire, *within* the shield of the cable. Now, I'd understand
> that if the serial lines were 'balanced' (floating return), but all the
> serial ground returns are electrically bonded to the chassis of the
> AF4500S. Any noise imposed on the shield goes to exactly the same place
> inside the unit as the separate ground return. Seems silly to run an extra
> ground wire that's at the same potential as the shield.
>
> Any thoughts on this from those who have either designed or done the
> actual work on a/c using ARINC 429 and/or serial port technology?
>
> Thanks,
>
> Charlie
>
> *
>
>
> *
>
>
Message 2
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Subject: | Re: ARINC 429 wiring practices |
I built nav processors for survey planes using several ARINC 429 devices
tied together. Twisted pair wire was sufficient although we used
shielded. Shielding for differential serial data like that is to reduce
electromagnetic interference (transmitted and received) among the other
systems, so tying the shield to chassis at one end should be fine. EMI
was the only place where we had problems, and in some cases we needed to
swap which end was shielded to get the quietest results. Some of our
signals used multiple pairs inside one shield and that worked fine. No
use for a separate ground wire.
David Josephson
Message 3
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Subject: | Re: ARINC 429 wiring practices |
>
>Any thoughts on this from those who have either designed or done the
>actual work on a/c using ARINC 429 and/or serial port technology?
ARINC 429 is implemented on aircraft of all
sizes wherein local grounds for appliances
can be yards apart and serial data is conducted
on wires that traverse the wild and wooly environs
for all manner of potential antagonist and victim.
The short story is that for a single-engine,
light aircraft with all the goodies mounted
on the panel and sharing local grounds, the
risks for loss of serial data signal integrity
are zero.
There is no value in adding any sort of ground
external to a shielded-twisted-pair . . . why
anyone would suggest such at thing is a mystery.
There is no value in grounding a shield at both
ends . . . shields on STP data lines are just that,
stop-gaps for electrostatically coupled noises
into or out of the lines which are already
protected by the physics of twisted, balanced
signal paths. Telephone companies have successfully
exploited this particular physics in the fabrication
and operation of phone lines in bundles with
hundreds of other signals and traversing horrible
environs over many miles.
The twisted, balanced pair is about as bullet
proof as you can get without shielding. Ground
the shields at either end and only once.
Bob . . .
Message 4
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Subject: | Re: ARINC 429 wiring practices |
Thanks for the pics. I suspected that the elaborate shielding described in
the ARINC docs was a bit of overkill, but I went ahead with actual shielded
twisted pair. I'm about 75% done at this point; should have waited a couple
of days. :-)
Charlie
On Mon, Jul 27, 2015 at 9:16 AM, Christopher Cee Stone <rv8iator@gmail.com>
wrote:
> Hello Charlie,
>
> My -8 panel is holds a 430W, AF4500, ARINC module, AF3500 and AF-pilot.
>
> I followed the AFS wiring schematic exactly. No shielded cables except
> for the run to the magnetometer and serial port connections. All remaining
> connections between the ARINC 429 module, the 430 and the AF4500 are AWG22
> single wire bundled into a harness with zip ties.
>
> I attached the ARINC 429 box to the underside of the AF4500 with self
> adhering velcro. Thus all signal wire runs are short, less than 24 inches.
>
> System works flawlessly.
>
>
> Chris Stone
> RV-8
> 80802
>
> On Sun, Jul 26, 2015 at 12:11 PM, Charlie England <ceengland7@gmail.com>
> wrote:
>
>> I'm in the process of wiring my panel, which includes an old Garmin 430
>> (non-WAAS), an AFS AF4500S EFIS, AFS ARINC module, and AFS Pilot
>> autopilot. I'm using the AF3000-4000 Installation Guide, v7.4. Looking
>> through the AFS docs, their wiring diagrams are a bit...inconsistent... on
>> how to treat the ARINC and serial port data wiring.
>>
>> So I did some digging in the InterWebs to find the 'proper' way to wire
>> ARINC 429 stuff. Two different sources say to ground the ARINC 429 shield
>> at source, destination, and at every 'break point' where additional
>> receivers are added, in daisy chain fashion. Easy enough; I can handle
>> that.
>>
>> There are 3 ARINC data runs between the ARINC module and the 430. Should
>> each get its own shielded twisted pair, or would it be kosher to run 3
>> pairs in one shielded cable (and/or variations on that theme)?
>>
>> In various places, there are both single and bi-directional serial runs
>> between/among the EFIS, 430, and other devices. In one case, they specify
>> that a ground return *isn't needed* (obviously depending on system
>> ground(s) between the EFIS & the 430). In most cases, they show a separate
>> ground return wire, *within* the shield of the cable. Now, I'd understand
>> that if the serial lines were 'balanced' (floating return), but all the
>> serial ground returns are electrically bonded to the chassis of the
>> AF4500S. Any noise imposed on the shield goes to exactly the same place
>> inside the unit as the separate ground return. Seems silly to run an extra
>> ground wire that's at the same potential as the shield.
>>
>> Any thoughts on this from those who have either designed or done the
>> actual work on a/c using ARINC 429 and/or serial port technology?
>>
>> Thanks,
>>
>> Charlie
>>
>> *
>>
>> ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List <http://www.matronics.com/Navigator?AeroElectric-List>
>> tp://forums.matronics.com <http://forums.matronics.com>
>> _blank">http://www.matronics.com/contribution <http://www.matronics.com/contribution>
>>
>> *
>>
>>
>
Message 5
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Subject: | Re: ARINC 429 wiring practices |
Thanks to David & Bob.
Bob,
My question about the 'extra' ground wire was related to the serial
port(s), not ARINC. IIRC, serial stuff is typically unbalanced, with a
signal line and a shield/ground return. In the case of the AFS docs, they
show in one case (to external GPS) a pair of signal wires (bi-directional
data), and a ground wire, all wrapped in a shield. In another case
(magnetometer) they show a pair of RS422 signal wires, a power wire, and a
ground wire, all wrapped in a shield. That's the practice of embedding an
extra ground wire inside a shield (when the shield can serve as ground)
that I was really questioning.
Charlie
On Mon, Jul 27, 2015 at 10:23 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
>
> Any thoughts on this from those who have either designed or done the
> actual work on a/c using ARINC 429 and/or serial port technology?
>
>
> ARINC 429 is implemented on aircraft of all
> sizes wherein local grounds for appliances
> can be yards apart and serial data is conducted
> on wires that traverse the wild and wooly environs
> for all manner of potential antagonist and victim.
>
> The short story is that for a single-engine,
> light aircraft with all the goodies mounted
> on the panel and sharing local grounds, the
> risks for loss of serial data signal integrity
> are zero.
>
> There is no value in adding any sort of ground
> external to a shielded-twisted-pair . . . why
> anyone would suggest such at thing is a mystery.
> There is no value in grounding a shield at both
> ends . . . shields on STP data lines are just that,
> stop-gaps for electrostatically coupled noises
> into or out of the lines which are already
> protected by the physics of twisted, balanced
> signal paths. Telephone companies have successfully
> exploited this particular physics in the fabrication
> and operation of phone lines in bundles with
> hundreds of other signals and traversing horrible
> environs over many miles.
>
> The twisted, balanced pair is about as bullet
> proof as you can get without shielding. Ground
> the shields at either end and only once.
>
> Bob . . .
>
> *
>
>
> *
>
>
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