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Dynon rx and tx with vp-x

southtarnation

Well Known Member
Im getting tx incrmenting but not the rx....



I have an issue i am hoping to get some feedback or a little help on.

I have a dynon 7" sv hooked to a vp-x sport. I am having an issue getting them to communicate. Specifically the tx rx function.

There are 5 sets of serial wires each with a tx and rx. The tx from one device hooks to the rx of the other device, pretty simple. I have dedicate the serial set 1 to the vp-x skipped sets 2 & 3 for now and used 4 for the xsponder and 5 for the gps.

In the dynon local display setup screen i have assigned the serial ports as outlined above. The gps is incrementing on the rx line and establishes a fix. The transponder (no antenna hooked up yet) is incrementing the tx line only, nothing on the rx. Im not sure if thats normal without an antenna, but most troubling is the vp-x. Using serial wire set "1" with tx hooked to rx and rx to tx. The setup page for the vpx serial connection only shows tx incrementing. Rx stays at zero.

I figured i had made a mistake and wired them up tx to tx and verified the wiring, ports and double checked both manuals as well as checking the ground and found it to be correct. I removed the wires from the connecters and reinserted them verifying they were seated correctly.

I contacted Vertical Power and they suggested i "ring out my wiring". So i repeated all of the above verifications again with the same results.

I thought that maybe it was that set of serial lines for whatever reason so i wired up the tx and rx for serial lines "2" and of course verified that all the pins were right and tx was to rx and so on with exactly the same results.

At this point im pretty sure that either the Dynon or vpx hardware or software may be the issue. Im very willing to try anything that can be tried to identify the exact issue.

All updates and lic keys have been applied with exception to the Dynon 5.0 release. In the network auto-detect feature all attached modules have been found with the exception of the servos. The servos have to be powered to be updated and found on the network but are wired to receive power and be switched through the vpx.

I had considered that maybe i was having issue getting any/all devices to increment on the rx side but the gps on serial set "5" is incrementing and providing a fix on the map. So far everything works as it should with the exception of the communication between the Dynon and vpx (huge part of the total picture) evidenced by the big red x over the vpx page on the engine page and the lack of incrementation on the rx side of the serial lines.

Any help from Dynon, Vertical Power or the VAF member base os appreciated greatly.
 
Do you have one or two SkyView screens in the plane?

The simplest thing to do is hook one of the TX wires to the RX wire on the SkyView. This creates a "loopback." Set up this port as VP-X or Transponder. If the SkyView is transmitting, then the RX counter should increase. If something is broken, then the RX will not.

The transponder should increase without an antenna, but only if it has power, and I assume you have that on the VP-X too. But can't you turn on the servos and the transponder with your switches for the VP-X?
 
Do you have one or two SkyView screens in the plane?

The simplest thing to do is hook one of the TX wires to the RX wire on the SkyView. This creates a "loopback." Set up this port as VP-X or Transponder. If the SkyView is transmitting, then the RX counter should increase. If something is broken, then the RX will not.

The transponder should increase without an antenna, but only if it has power, and I assume you have that on the VP-X too. But can't you turn on the servos and the transponder with your switches for the VP-X?

Thanks for rhe reply.
I have just one 7"skyview. I didnt think about the transponder being powered through the vpx. I do not have any of the physical switches hooked up as tbey are aveo rockrack and on backorder until feb 1st. I have hooked up an infinity grip with the ap disconnect, elevator trim, boost pump and starter and have loaded my configuration from the vpx configurator onto the vpx. I was hoping to get thing going using the soft switch function of the vpx through the dynon.

Im afraid that i have tried what you suggest above with serial TX wires from the vpx to the RX wire on the SkyView for both of the rx sides of the serial sets 1 & 2 with the same results.

Unfortunatly the airplane is 100miles away and i have to fly to it on weekends to work on it. Trying a different set of serial wires and verifying the correct wires and ports is what i did last weekend, the weekend after firing it up amd finding the issue. This weekend i would like to have a new course of action. It seems as hard as i want it to a simple wiring mistake that as you said something is broken. With whats described can you make a determination on if it would be the dynon or the vpx? Or what i could do to differentiate which pne is at fault?

Thans again,
Jesse

EDIT: i just reread what you suggested and i misunderstood that you are saying to hook the rx and tx wires from the dyon only together (loopback) and checking for incrementing on both sides after setting it up as vpx in the setup. Good deal, thanks. Should i try all 5 sets to verify, i guess i might as well?
 
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Based on the hardware inside, if you try port 1 and then port 3 or 4 you are testing different paths inside the box.
 
Don't run the transponder without an antenna or dummy load!

Ok, ill hook an antenna to it for future tests.
Why is that? And what could be used as a dummy load?

Based on the hardware inside, if you try port 1 and then port 3 or 4 you are testing different paths inside the box.

Ok. Pretty unlikely that more than one "path" would have issues but as easy as you say it is to test by connecting the tx and rx lines of each serial pair from the dynon together, i may as well test all 5 pairs. Why not?

If i get the tx and rx lines each to increment and even verify that all 5 pairs are as well than its safe to say its the vpx? Or still my wiring/harnesses...

Thanks!
 
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On the VP-X side, you can turn on and off circuits from within the Configurator app when it's connected to the VP-X, and you also can see the TX/RX status in the system status page. Since switch assignments are easily changed around in Configurator, you can also assign a few of your stick switches to temporarily control the devices you are testing (until your regular panel switches arrive). These systems integration issues can feel difficult when you encounter them, but we have many Skyview/VP-X installations working without a hitch, usually from the first time they're connected together, so it's safe to assume (but not guaranteed) that the problem will turn out to be wiring (with configuration or hardware failure possible but rare alternatives).

--
Stephen
 
I guess I am still from old school, where if you run the transmitter without and antenna you will definitely do damage. It's good that the new equipment has protection. I stand corrected, at least with the Dynon xponder.
 
I guess I am still from old school, where if you run the transmitter without and antenna you will definitely do damage. It's good that the new equipment has protection. I stand corrected, at least with the Dynon xponder.

Good points Bill,
The new mode S xpdrs with ES transmit even without being interogated, I know at least some xpdrs can be damaged without an antenna or dummy load connected. I will not operate any of the ES xpdrs without a antenna or load installed (warranty may not cover this if the unit is damaged). Transmitting into an open will/can damage many transmitters and is not a good practice regardless.
 
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Sorry, I didn't mean to insinuate that operating without an antenna was a good practice or OK with other equipment. Just in this specific case, with this specific transponder, you don't need to worry about that. Just trying to save the poster some hassle in determining his issue.

Unless the manufacturer specifically states that it's OK, as Walt and Bill say, never operate a transmitter without an antenna or dummy load connected.
 
dynonsupport; said:
The simplest thing to do is hook one of the TX wires to the RX wire on the SkyView. This creates a "loopback." Set up this port as VP-X or Transponder. If the SkyView is transmitting, then the RX counter should increase. If something is broken, then the RX will not.

Tried the above test today...

Set serial one in the dynon to vpx and loop backed the tx and rx. It incremented on both, so not a dynon issue. Tried serial 2 loopback and got tx and rx incrementing. Ok. So triple checked mire diagrams and wires and re-connected serial set 1 to the vp-x turned it all on and still have the same issue of the vpx not incrementing on the rx side.

Is there anything else that could cause this aside from a hardware issue with the vpx?

I have everything wired up except the comm and xcom, any panel switches (stick switches wired up) or anything on the "back" engine side of the ems module. The ems is connected to the the display though. Servos are connected hut trim is not yet.

It would seem like and i would rather it be me and a wiring mistake than a brand new out of the box piece of hardware that im staking my safety on for a big part...

Thanks for any feedback.
 
Jesse,
Have you loaded a configuration file to the VPX? Have ou connected a computer to the VPX Ethernet port. Btw, only the top port is enabled? If you have it connected, is it communicating properly with the VPX? Is your equipment connected to the VPX and more importantly, does it have power?
Bill
 
Jesse,
Have you loaded a configuration file to the VPX? Have ou connected a computer to the VPX Ethernet port. Btw, only the top port is enabled? If you have it connected, is it communicating properly with the VPX? Is your equipment connected to the VPX and more importantly, does it have power?
Bill

Yes config file loaded vie laptop and ethernet cable.

Top port? On the vp-x? Yes im using/did use the correct ethernet port on the vp-x.

It did communicate/connect once i shut the wifi off. Then i uploaded my config file.

Yes power to the main power bolt on the vpx which causes the dynon to then come on. I have the orange light on the vpx, dynon screen works, has gps fix even...

Any more ideas? And thank you for your help.
 
I'm sure that you have set up the configuration of the ports on the dynon for the correct speeds etc. I am not familiar with the dynon, I am using the VPX with the g3x. I know you have probably already checked, but do you have the serial lines wired correctly. I am assuming you used 2 conductor shieled and have the shield terminated properly. Are you reading the connector pins correctly? Did you ring out the wires by actually touching the connector pins end to end? Did you check for a short from the conductors to the shields?
There is always a chance that the rs232 IC in the VPX is bad, but unless improper power was applied to it, I would doubt it. When you did the loop back test did you actually loop the wires from the VPX connector back to the dynon. Try running 2 new wires from the dynon to the VPX crimp new pins at both ends.
I don't have any more ideas. Send the VPX back and heave them verify the serial port is working properly
Bill
 
I'm sure that you have set up the configuration of the ports on the dynon for the correct speeds etc. I am not familiar with the dynon, I am using the VPX with the g3x. I know you have probably already checked, but do you have the serial lines wired correctly. I am assuming you used 2 conductor shieled and have the shield terminated properly. Are you reading the connector pins correctly? Did you ring out the wires by actually touching the connector pins end to end? Did you check for a short from the conductors to the shields?
There is always a chance that the rs232 IC in the VPX is bad, but unless improper power was applied to it, I would doubt it. When you did the loop back test did you actually loop the wires from the VPX connector back to the dynon. Try running 2 new wires from the dynon to the VPX crimp new pins at both ends.
I don't have any more ideas. Send the VPX back and heave them verify the serial port is working properly
Bill

Im not aware of the need or the abuility to changes speeds and dont recall it mentioned wirh regards yo the Dynon. Ill look into that, maybe you are onto something I missed.

Im confident that i have the 3 wires hooked up correctly. Tx to rx and rx to tx. The ground is confirmed to be good and also wired up correctly. I did noy use shieleded 3 wire though, I used 3 seperate 18g wires.

For the loopback test, i disconnecged the vpx harness the housed the serial 1 rx and tx wires from the dynon. I removed the wires for tx and rx from the dynon out of the vpx harness and hooked them together with the dsub pins still attached the ends. I then loacted and gested serial set 2 directly off the sv harness since no other wires were connected to them yet. In both cases i found that the tx and rx incremented. Tried set 1 and set 2 again with the serial connection for the set being tested set to the vpx within the dynon setup with the same results. Tx but no rx when connected to the vp-x.

Thanks for your input!
 
Jesse,
You should always use twisted, shielded wire for all of the connections with the exception of power. The shields should always incorporate a single point ground, that is, only grounded at one end, unless specified otherwise. Does the dynon have a separate return (gnd) for their 232 ports?
I will make a suggestion that you have an avionics tech take a look at your harness
Page 4-15 of the sky view install man shows how to configure the serial port
Bill
 
Jesse,
You should always use twisted, shielded wire for all of the connections with the exception of power. The shields should always incorporate a single point ground, that is, only grounded at one end, unless specified otherwise. Does the dynon have a separate return (gnd) for their 232 ports?
I will make a suggestion that you have an avionics tech take a look at your harness
Page 4-15 of the sky view install man shows how to configure the serial port
Bill

The vpx man has the ground from port 22 being hooked to the two grounds from the the skyview harness, cant remember the port numbers, but it is per the manual.

Section 4-15 specifies to choose the manufacture of the equipment being hooked up if available, which the vp-x is. It autopopulates the settings and cannot be changed once selected.

Im sure you are correct about using twisted shielded, it would mean adding wire to the sv harness, length i dont need. As it is i put pins right on the serial wires from the dynon and plugged them directly into the vpx harness. There is a ground on each harness that needed to be hooked together so i dont think it was applicable to use shielded.

Is it even possible that the wires not being shielded could cause my issue? I would have to start deconstrcting the sv harness to make it shielded, twisted the whole way...

I pulled the vpx and will see about sending it back. If anyone wants to offer to look at my harness though, another set of eyes would never hurt and ill buy lunch. Planes in south lakeland.
 
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Jesse,
Have you done a continuity check on the lead in question? Also,it sounds like the pin of that lead may not be making contact in the female connector. If that checks out ok, try changing to a different set of tx and rx wires. Ex. instead of # 1 use # 2 or 3.
I had to change one of mine to another set of wires.
Dave
 
Jesse,
Have you done a continuity check on the lead in question? Also,it sounds like the pin of that lead may not be making contact in the female connector. If that checks out ok, try changing to a different set of tx and rx wires. Ex. instead of # 1 use # 2 or 3.
I had to change one of mine to another set of wires.
Dave

Yes, I've done continuity checks from harness to harness and it checks out good.
I looked at the pons and they are all seated and the proper length inside each connector.

I also tested (loopback) serial lines 1 & 2. Both checked out so i first tried set 1 again with mo joy and then set 2 with the same results.

Thanks though,
Jesse
 
Here's a few thoughts Jesse:

You mention the use of individual 18 AWG wires. The standard size (size 20) d-sub connectors used on the VP-X and SkyView are designed for 20-24AWG wire, so you probably had to cut a few strands off to make it fit in the connectors. While 18 AWG will work electrically, we recommend using 20, 22 or 24 AWG 3 conductor shielded wire. The three wires carry RX, TX, and serial ground. The shield is wired to the airframe ground per standard practices. The shielding reduces the chance of interference from everything from nearby wires to radars, etc. So it'll probably work most of the time. In any case, the 18AWG wire is not the source of your specific problem herein, but may be a problem in the future.

You can connect the Configurator to the VP-X and under the System Info page look next to the 'External Data Missing' field. If there is an exclamation point symbol then it is not receiving the SkyView data. However, there is no way to perform a loopback test.

We'd be glad to look at the VP-X for you if you think the wiring is ok. Just send it in with a note explaining the issue and where to send it back.
 
You can connect the Configurator to the VP-X and under the System Info page look next to the 'External Data Missing' field. If there is an exclamation point symbol then it is not receiving the SkyView data. However, there is no way to perform a loopback test.

We'd be glad to look at the VP-X for you if you think the wiring is ok. Just send it in with a note explaining the issue and where to send it back.

Got out to the hanger today and ran the configurator utility...
Next to the "external data field" there IS an exclamation mark in red flashing. When i hovered the mouse over it, it popped up a short message saying it was not getting data from the efis.

Aside from the wiring and aside from any hardware issue; are there any settings that could be causung the issue. A friend suggested checking to see that the baud rates matched. Im pretty sure that when vpx is selected on the Dynon serial set up page that thenspeeds and other serial connection fields/settings are pre-filled out and grey out indicating the settings cannot be changed. Are there settings within the vpx to set the speed for the serial connection to the efis?

I am changing the n number of the plane and though maybe i entered different numbers on the dynon vs the vpx but checked and they are the same.

If there is nothing left i can check or do, I guess ill return the unit for your team to lookover.
 
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Do you have your AHRS hooked up to the EFIS and showing attitude already? This is where all the data we send to the VP-X comes from, and if it's not there we won't be sending it.

You cannot select the baud rate on SkyView or the VP-X, it's all automatically configured.
 
Jesse,
Does the AHARS display proper information and does the screen show airspeed etc. Does the GPS show your location. In general, is everything working with the Dynon except showin the VPX data? Are you absolutely sure your grounds are correct> I looked at the install manual and it appears that the ground (return) on the vpx is pin J1- 21, earlier you mentioned pin 22, are you sure you have the pins correct
J1-21 gnd
J1-22 Rx
J1-20 TX
And on the Skyview, use any pin 21-24 for the ground

From their manual:
Notes on SkyView installation:​
?​
TX = transmit port, RX = receive port, GND = ground.

?​
Use any open serial port pair on SkyView.

?​
Use any GND pin 21-24 on SkyView.

?​
Use 3 conductor shielded wire. Solder wires together within d-sub
hood and cover with heat shrink. Run single wire into d-sub pin.

?​
The SkyView has two power pins on the display. These two
power pins are simply to spread the load of a single power input
across two power pins. These two power inputs must be soldered
together into a single power wire. DO NOT wire each power pin

on the SkyView to its own power pin on the VP-X. (see diagram
 
Unfortunately, yes I'm sure. I may have misspoke in the post earlier as i was posting from memory. I have (and 3 others) verified that ports 20-22 are correct.

Everything you specified from the man was done with the exception of the shielded wire. Lol, which i see you put in bold.

Thanks for your help.
 
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but do you have the ground from j1-22 on vpx over to skyview pin 21-24? the serial port needs a return path to work. You caught me on the shielded wire, it really is important for good consistent operation.
 
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I have to disagree a bit with the statements made in here about shielding and grounds for RS-232.

You'll notice that on the SkyView harness, there is no specific ground for RS-232 ports, nor are the 3' of wire we supply for each of the 5 serial ports shielded. We didn't do this to cheap out, we did it because we don't believe shielding or grounding is needed in 99.99% of installs.

Shielding is there to either keep noise in a cable (like RF coax) or keep it from getting in a cable (like a microphone cable). SkyView uses slew rate limited serial drivers, which means they do a good job on not creating RF noise. Thus, you are not trying to keep noise from getting out of the cable, and if even if this was the issue, this would do nothing to make communications more reliable, which is the issue here.

RS-232 is a high voltage communications protocol (relative to most; I'm not saying it is going to shock you). It uses higher voltages because this makes the system more noise immune, and it specifically gives up power consumption and speed to do this. In order for outside noise to be an issue to RS-232, it has to be noise on the order of volts, and that would be a crazy amount of RF energy to get into a wire, especially one that is only a few feet long, like it would be between a SkyView and a VP-X. You'd likely have lots of other issues if this much RF energy was bouncing around the plane. RS-232 is also a relatively low impedance load so a lot of the noise gets knocked down by this.

As for grounding, the whole aircraft shares the same ground. SkyView has a nice ground to the battery, and so does the VP-X. Again, in order for ground to be an issue, there would have to be noise on the ground on the order of volts, which would cause huge issues in other places long before it caused serial problems. Adding a little 22 gauge ground wire between SkyView and your other serial device isn't going to make any difference against the whole plane as a gigantic ground. Remember, if your grounds are bad, adding a small wire in parallel doesn't magically fix the problem, it just shunts huge current into that small wire and likely causes it to melt. You need to make sure SkyView and your other devices have really good grounds to the aircraft's ground as a whole and not just between one another. The former automatically takes care of the latter.

Southtarnation has done the test where he hooked the output of SkyView back into the input of SkyView. This worked, and showed data being received into SkyView. This proves a lot: SkyView is outputting data, the cable is solid, and SkyView can receive data as well. Shielding and grounds here are not the issue. I realize that this test does not test for ground, but there is no way the VP-X and the SkyView have a 3V difference on their grounds. On top of this, he's having an issue in a system that doesn't even have a radio or transponder on line, so it's not like there is a lot of RF energy in the plane. Finally, he is getting absolutely zero data back from the VP-X when he's hooked to it. Noise will not cause zero data. It will cause corrupt data, but SkyView will clearly show this as received but corrupt data, not no data at all.

Shielding is needed in a lot of places, such as RF transmission lines, and really sensitive circuits like microphones where millivolts of noise are audible. RS-232 is just plain immune to the small voltages that you might encounter with the short runs you make in a homebuilt plane.

I realize there are some simplifications in the above description, and you can imagine corner cases where shielding would help. But when someone says "my RS-232 device flat out never communicates properly and never seems to transmit a single bye," shielding and grounds are unlikely to be the issue.

--Ian Jordan
Dynon Avionics
 
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While I agree with some of what you said Ian, it is still the convention and good practice to shield all data communication, RF and audio wires, whether to help supress radiated emissions or decrease suscepability to the same. It is the gold standard. I would never wire a panel without. Further, it's called out in most every avionics manual I have ever read. In the long haul, its just another form of protection.

Assuming the transponder is not radiating, then I don't recall that there were any other RF sources, so you are correct, this issue does not appear to be a source of noise on the 232 lines, and they appear to be wired correctly.

At this point, after all of the tests you've run Jesse, I would send the VPX back to have it tested and go from there. Please let us know what you find out
Bill
 
Thanks!

Marc at Vp offered to take a look at it so ill mail it off asap.

With regards to the shielding; it does seem like that shielding couldnt hurt but since the dynon harness serial lines are not, it would mean that i would have to deconstruct the dynon harness to have shielded the full length or add shielded to the harness in which i would be addid length i dont need and still would have the lenght of unshielded too.

Im curious which you did? Did you add to the efis harness with shielded or did your efis's harness already have shielded or did yoo make your own harness?

Like you guys agree, this is not a grounding or shielding issue and seems to be within the vpx settings or hardware.

Thanks for everyones help, Ill report back what comes of this.

Jesse
 
Great news, Jesse! We received your VP-X Sport this morning and immediately hooked it up to our Dynon SkyView on our test bench. Without any changes to the configuration of your VP-X, the box worked flawlessly. The serial communications between your VP-X and our SkyView are working fine. We'll ship your unchanged unit back to you today.

So again, when you get your unit back from us, you should be looking for the source of the problem in your wiring. I recommend you try to simplify the topology as much as possible, and get that working first, before gradually approaching whatever complex topology you require. Specifically, try connecting just a single SkyView screen and your VP-X on your test bench. Use the recommended gauge wires, and double and triple check that you are using the correct pins (pin misidentification is the number one problem I've seen customers have).

We'll continue to be happy to help you track down this problem. Let us know what we can do to help.

Best wishes,

Stephen
 
I haven't got the unit back yet but I was hoping that maybe I had misread the labeling on the actual connector but after looking with a magnifying glass I think I have the right holes.

The holes on the bottom row correspond to the number the bottom right, correct?

Here is my harness. Starting on the bottom left:
25 - empty
24 - empty
23 - empty
22 - serial/white tx
21 - ground/black to dynon
20 - serial/white Rx
19 - pos sensor
18 - pos sensor
17 - pos sensor

Hope someone sees my mistake...

blogger-image-1010635582.jpg


blogger-image-86313549.jpg
 
Hi Jesse,

If this is the DB25 (J1) that connects to the VP-X, could you have pins 20 and 22 swapped? pin 20 is serial TX and pin 22 is serial RX (from VP-X), you show them as:

22 - serial/white tx
21 - ground/black to dynon
20 - serial/white Rx

So they may be backwards.

Pin 20 serial TX on the VPX should go to serial RX on the Skyview. (pins 3,5,7, or 9)
Pin 22 serial RX on the VPX should go to serial TX on the Skyview. (pins 4,5,6, or 10)
 
Jesse,
I believe you have the pins incorrectly connected. Viewed from the back of the connector as it is pictured in the top photo, pin 1 is top left, pin 13 top right, pin 14 bottom left, pin 25 bottom right. This would indicate that the black wire, which you stated was dynon ground, is in pin 18. You have the connector reversed. If you would like, give me a call I pm you my number.
 
Jesse,
I believe you have the pins incorrectly connected. Viewed from the back of the connector as it is pictured in the top photo, pin 1 is top left, pin 13 top right, pin 14 bottom left, pin 25 bottom right. This would indicate that the black wire, which you stated was dynon ground, is in pin 18. You have the connector reversed. If you would like, give me a call I pm you my number.

Bill. Thank you. I used a magnifying glass and I thought I could confirm that the pins were numerically ordered from left to right on the top and from right to left on the bottom when viewed from the back. Ill change it and if that's it I will need to check the other harnesses. ...and buy you lunch!

Hope you had a good trip to FL, are you home again now?
 
Hi Jesse,

If this is the DB25 (J1) that connects to the VP-X, could you have pins 20 and 22 swapped? pin 20 is serial TX and pin 22 is serial RX (from VP-X), you show them as:

22 - serial/white tx
21 - ground/black to dynon
20 - serial/white Rx

So they may be backwards.

Pin 20 serial TX on the VPX should go to serial RX on the Skyview. (pins 3,5,7, or 9)
Pin 22 serial RX on the VPX should go to serial TX on the Skyview. (pins 4,5,6, or 10)

Thanks for the input. My labels are the dynon side tx and Rx so we are in agreement it just wast clear from my post wich Rx or tx I was specifying.
 
Jesse,
I gave you a female connector pin out. I was incorrect, in that you have a male connector.

The pins for a male connector are as follows as viewed from rear with the wide side up. Pin 1 top right, pin 13 top left, Pin 14 bottom right, pin 25 bottom left.

In this case your connector is wire correctly, assuming that you have the RX and TX lines on the correct pins.

Sorry about my confusion!

Bill
 
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Great news, Jesse! We received your VP-X Sport this morning and immediately hooked it up to our Dynon SkyView on our test bench. Without any changes to the configuration of your VP-X, the box worked flawlessly. The serial communications between your VP-X and our SkyView are working fine. We'll ship your unchanged unit back to you today.

So again, when you get your unit back from us, you should be looking for the source of the problem in your wiring. I recommend you try to simplify the topology as much as possible, and get that working first, before gradually approaching whatever complex topology you require. Specifically, try connecting just a single SkyView screen and your VP-X on your test bench. Use the recommended gauge wires, and double and triple check that you are using the correct pins (pin misidentification is the number one problem I've seen customers have).

We'll continue to be happy to help you track down this problem. Let us know what we can do to help.

Best wishes,

Stephen

What are the minimum components I should start with?
My "system" only uses one screen.
I believe that the engine/ems module has to be hooked up, all wires (power, grounds and serials) between the vpx and sv7. And power and ground to the vpx unit. Are there any other minimum operation components or wiring that should be installed to troubleshoot the vpx to dynon comm issue?

Can you point me to a diagram of the physical ports on the harnesses?

Regards,
Jesse
 
I know you've said you checked your wiring, but like most things with these newer boxes, almost 99% of install issues are user induced....so that's where to start (which you did, but didn't find any issues). Are you absolutely 100% certain that you didn't accidentally hook a "Tx" to a "Tx" and an "Rx" to an "Rx"? This is a very, very common error with folks hooking up serial ports and the like. If Vertical Power tested your boxes with no issues, then that leaves the most likely problem to begin with....your wiring (on one end or the other, or in between, or with crimps, etc.). Simply ringing pin to pin for individual continuity won't necessarily give you the answer if you happen to have one pin touching another in the connector, a pin touching ground, or if you verified an induced error that you don't know you've made. Also, are there any splices/joints in between your harness, and again, are you certain you have the right wires going to the right place? It also is possible there is a configuration or other issue with your Skyview, though it's less probable than a wiring problem.

I don't know the answer, but I do know it's just a matter of taking it one wire at a time and fining out what is going on. Perhaps just whip up a new and quick jumper harness to test (like what VP used or what we use) to see?

Sorry I don't have a good answer, but the answer has to lie there somewhere.

Cheers,
Stein
 
Jesse,
It seems you have spent an inordinate amount of time with this issue. I would suggest that you consider having someone fabricate an entire harness for your application. In the long run, you may find that it costs less than the possibility on damaging your expensive avionics. Possibly a local avionics shop. I would create a drawing of your requirements and get a quote.
Setting the above aside, Stein offers a lot of good ideas. You know the equipment works properly, so it must be a wiring error. Start one wire at a time....
Bill
 
Thanks for the additional input guys. I rolled my fuse this weekend in prep for painting the bottom so I wast able to do a lot of troubleshooting while I was there this time but will be troubleshooting each wire next weekend. Ill also try to simplyfy the system and do a bench test too.

Stein, I have triple checked that tx is to Rx. I do have a splice in serial set 1, so I added connectors directly to the sv harness for serial set 2 and substituted serial set 2 for 1 in the vpx harness and made all the necessary software changes in the dynon set up with the exact same results. Incrementing on the tx to the vpx but 0 on the Rx from the vpx. Based on that test it's isn't the serial wires or splices as they all loop back fine. I have triple checked the ports and got another set of eyes to verify. The info connection seems to be failing after the tx enters the vpx harness as no return info is received back out. I did all of my loop back tests on the serial lines by removing them from the vpx harness and holding the pins together. I think then that the puns are installed correctly to the wires. Should I loop back test serial lines while they are still in the vpx harness?

By process of elimination I think that the issue is with my ground. Will a bad ground (grounding block not well grounded) cause the issue of tx incrmenting but not Rx? While leaving everything else apparently grounded well enough to operate? (Like the sv screen)

Thanks again!
 
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By process of elimination I think that the issue is with my ground. Will a bad ground (grounding block not well grounded) cause the issue of tx incrmenting but not Rx? While leaving everything else apparently grounded well enough to operate? (Like the sv screen)

Thanks again!

Try a short temporary jumper cable tying the cases of the two devices together as a quick test of your grounding....
 
The idea of a basic harness is a good one.

SkyView will boot and operate with just power and ground connected. If you build a D37 with power, ground, serial X TX and serial X RX, then you only have 4 wires to worry about.

Then hook the TX and RX to the VP-X, and if it doesn't work, reverse them. There is no chance of electrical damage from reversing TX and RX.

If that works, then you can go back to your main harness and see what is different.
 
The idea of a basic harness is a good one.

SkyView will boot and operate with just power and ground connected. If you build a D37 with power, ground, serial X TX and serial X RX, then you only have 4 wires to worry about.

Then hook the TX and RX to the VP-X, and if it doesn't work, reverse them. There is no chance of electrical damage from reversing TX and RX.

If that works, then you can go back to your main harness and see what is different.

This is exactly what I'm gonna do. Thanks for the confirmation. I will be able to see both the Rx and tx lines incrementing from the setup page. So no need to plug in the ems module until after that has been verified? I'm pretty sure that to see the "vpx page" on the dynon display I'll need the ems connected?
 
True, you will need to have the EMS module plugged in, but since this goes to a separate connector, it won't get in the way. I can't imagine any way anything on the SkyNet network would be causing you issues.
 
EFIS Power correct

Hi Jesse,
This is a long shot but did you see the note 1 on the VP wiring diagram? It says:
"Serial must be wired to same EFIS that is powered by J12-9'

Did you power the Skyview from J12-9 on the VPX? If not, maybe that could be causing the problem.
 
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