---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 07/27/15: 5 ---------------------------------------------------------- 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 _____________________________________ Time: 07:18:52 AM PST US Subject: Re: AeroElectric-List: ARINC 429 wiring practices From: Christopher Cee Stone 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 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 _____________________________________ Time: 08:10:20 AM PST US Subject: AeroElectric-List: Re: ARINC 429 wiring practices From: David Josephson 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 _____________________________________ Time: 08:24:40 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 12:57:02 PM PST US Subject: Re: AeroElectric-List: ARINC 429 wiring practices From: Charlie England 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 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 > 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 >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> >> > ________________________________ Message 5 _____________________________________ Time: 02:36:10 PM PST US Subject: Re: AeroElectric-List: ARINC 429 wiring practices From: Charlie England 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 . . . > > * > > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.